Home

Documentation for ANSYS ICEM CFD 12.1

1. sssessssseeeeeeeee eene eene eene nennen essen een n nnne nnns 39 Blocking Strategy asiento in etea op pest olt vs UN Moped t petu v epe leno de vast estos e dio 39 Hexa Block TYPES T 40 So Li Ena EA E E E A E A E E E E ANEA A E 41 jl A E AEE E AA A E E E EE T EE A EEE 41 Usingithe Automatic O grid aaaeeeaa e sub d Eo O dd ee Ge eni ERR quy di Fro ERO DE 41 Most Important Features of Hexa esses eene nennen sese en nennt nene sese ener nenne seen enn 42 Automatic O gnd generation i cot rro rr ct erp p Eo tare AER a Guana ERAT x Mea e 43 Important Features of an O grid ode dao coim oe Du Ee petet i edic apre deer ae ult ccn Du aes 43 Edge Meshing Parameters swe cope tertie hte eap cobre uda dh E NN ROBES vuba momenta EAE Qe OO LU Au 43 Smoothing Techniques yes ss op err Er DATEI REV EEE EAD EE AM sane cp Ur va ER e I e E eue a poo ada 44 Refinement and COdFSehlfTO erien eere donner xv posui ini ups Cree deat oman nano an pier eoa dedu 45 Refinement einnar TH e o TRE 45 e ICT e 45 Replay Functioniallty xiva We ap e dod viec ACH DS raggi a i area e M UA IO e Ete b Muse raa p a 45 Gerieratinig a Replay File dert 45 Advantage of the Replay FUNCHON scade caiwsaeransecaiweasaudeconsedwemaqned RA PRO PAY CENE MS NN ERI TX VASA HUE 45 Using Variables in the Replay Script otto vn oH C ei edet e etd x eee p e Debr ed e ON EUER 45 Periodicity INN EIU D ONCE 46 Applying
2. ANSYS ICEM CFD 12 1 2009 SAS IP Inc All rights reserved Contains proprietary and confidential information of ANSYS Inc and its subsidiaries and affiliates 57 58 ANSYS ICEM CFD 12 1 2009 SAS IP Inc All rights reserved Contains proprietary and confidential information of ANSYS Inc and its subsidiaries and affiliates Solve Options Setup Solver Parameters has options for specifying the solver parameters You can also specify the analysis solution and postprocessing parameters For more useful information about Solver Options please go to this page Setup Solver Parameters You can select from the following solvers ANSYS Nastran ABAQUS AUTODYN and LS Dyna Setup Analysis Type Depending on the selected solver different options are available For the ANSYS solver you can select either Structural or Thermal If Nastran solver is selected then you have the choice of more Analysis types Setup Sub Case You can create subcases to apply the load in different steps Write View Input file You can create and view the input file generated for the solver Submit Solver Run Using this option you can solve the input file generated for a particular solver Post Process Results This option allows you to plot the results FEA Solver Support For more useful information on FEA Solvers Support please go to this page ANSYS ICEM CFD 12 1 2009 SAS IP Inc All rights reserved Contains propri
3. User Manual ANSYS Inc ANSYS ICEM CFD 12 1 Southpointe November 2009 275 Technology Drive ANSYS Inc is Canonsburg PA 15317 certified to ISO ansysinfoGansys com 9001 2008 http www ansys com T 724 746 3304 F 724 514 9494 Copyright and Trademark Information 2009 SAS IP Inc All rights reserved Unauthorized use distribution or duplication is prohibited ANSYS ANSYS Workbench Ansoft AUTODYN EKM Engineering Knowledge Manager CFX FLUENT HFSS and any and all ANSYS Inc brand product service and feature names logos and slogans are registered trademarks or trademarks of ANSYS Inc or its subsidiaries in the United States or other countries ICEM CFD is a trademark used by ANSYS Inc under license CFX is a trademark of Sony Corporation in Japan All other brand product service and feature names or trademarks are the property of their respective owners Disclaimer Notice THIS ANSYS SOFTWARE PRODUCT AND PROGRAM DOCUMENTATION INCLUDE TRADE SECRETS AND ARE CONFIDENTIAL AND PROPRIETARY PRODUCTS OF ANSYS INC ITS SUBSIDIARIES OR LICENSORS The software products and document ation are furnished by ANSYS Inc its subsidiaries or affiliates under a software license agreement that contains pro visions concerning non disclosure copying length and nature of use compliance with exporting laws warranties disclaimers limitations of liability and remedies and other provisions The software products and document
4. Using wildcard characters to search for expressions with identical characters Using parentheses to nest search expressions The Search tab in the Help also includes check boxes located at the bottom of the panel that allow you to search previous results match similar words or search titles only ANSYS ICEM CFD 12 1 2009 SAS IP Inc All rights reserved Contains proprietary and confidential information of ANSYS Inc and its subsidiaries and affiliates 13 14 ANSYS ICEM CFD 12 1 2009 SAS IP Inc All rights reserved Contains proprietary and confidential information of ANSYS Inc and its subsidiaries and affiliates CAD Repair Before generating the mesh you should confirm that the geometry is free of any flaws that would inhibit optimal mesh creation If you wish to save the changes in the native CAD files the following checks should be performed in a direct CAD interface Tocreate a mesh the Tetra mesher requires that the model contains a closed volume If there are any holes gaps or missing surfaces in the geometry that are larger than the local tetras the Tetra mesher will be unable to find a closed volume Thus if you notice any holes in the model prior to mesh gener ation you should fix the surface data to eliminate these holes The Build Topology operation will find holes and gaps in the geometry It should display yellow curves where there are large in relation to a user specifie
5. plane with one another will produce a element with small warpage Nodes that make elements twisted or distorted will increase a element s distortion giving a high degree of warpage The y axis is the scale for the number of elements represented in the histogram a value determined by the assigned Height The x axis which ranges from a Min of 0 to a Max of 90 is the degree of warpage that a elements experiences ANSYS ICEM CFD 12 1 2009 SAS IP Inc All rights reserved Contains proprietary and confidential information of ANSYS Inc and its subsidiaries and affiliates 47 48 ANSYS ICEM CFD 12 1 2009 SAS IP Inc All rights reserved Contains proprietary and confidential information of ANSYS Inc and its subsidiaries and affiliates Properties The Properties menu allows you to create different materials by specifying material or element properties such as type the Young s Modulus and Poisson s ratio Once the material is created you can apply those properties to the elements Create Material Property Here you can define a material by specifying a name of the material define whether isotropic enter in values for Young s Modulus Shear modulus Poisson s ratio Mass Density and Thermal expansion coefficient Save Material This option allows you to save the material which is created so that you may retrieve the material whenever necessary The material file will be saved with the mat extension Open
6. All the files required for a particular analysis are contained within a Project You can either open an existing project or create a new project The Project directory typically contains one or more of the following file types Tetin tin contains geometry entities material points part association and global and entity mesh sizes Project Settings prj contains the project settings Domain uns contains the unstructured mesh Blocking blk contains the blocking topology Boundary Conditions fbc contains boundary conditions ANSYS ICEM CFD 12 1 2009 SAS IP Inc All rights reserved Contains proprietary and confidential 2 information of ANSYS Inc and its subsidiaries and affiliates Creating the Mesh Attributes atr contains attributes local parameters and element types Parameters par contains model parameters and element types Journal jrf contains a record of operations performed echo file Replay rpl contains the replay script Creating Manipulating the Geometry ANSYS ICEM CFD includes a wide range of tools for creating new and or manipulating existing geometry You can either alter complex geometry or create simple geometry without having to go back to the original CAD This can be done for CAD NURBS surfaces and triangulated surface data The ANSYS ICEM CFD Direct CAD Interfaces provide the bridge between parametric geometry creation tools available in CAD systems and
7. Figure Hole Within a Single Surface Figure After Remove Holes p 16 shows the geometry after the Remove Holes operation is completed for one of the holes The existing surface is modified by removing the trim definition Figure After Remove Holes ANSYS ICEM CFD 12 1 2009 SAS IP Inc All rights reserved Contains proprietary and confidential 16 information of ANSYS Inc and its subsidiaries and affiliates Fill Trim and Blend in Stitch Match Edges Fill Trim and Blend in Stitch Match Edges Consider the case of a geometry with a gap shown in Figure Geometry With a Gap p 17 Figure Geometry With a Gap Figure Using the Fill Option p 17 shows the use of the Fill option Figure Using the Fill Option Figure Using the Trim Option p 17 shows the use of the Trim option Figure Using the Trim Option Figure Using the Blend Option p 18 shows the use of the Blend option ANSYS ICEM CFD 12 1 2009 SAS IP Inc All rights reserved Contains proprietary and confidential 17 information of ANSYS Inc and its subsidiaries and affiliates CAD Repair Figure Using the Blend Option Match in Stitch Match Edges The Match option is generally used in those cases where curves lie very close to each other specifically when the two ends meet together see Figure Geometry With Mismatched Edges p 18 and Figure Geometry After Using the Match Edges Option p 19 You shoul
8. Material This option allows you to open a material file so that you can use the same in future or modify the file and save for further usage Define Table You can create different tables by specifying the values for x and y and can even visualize the graph Define Elements Although the mesh has been created you need to apply the material created to the respected elements Different types of elements that can be defined include Point Line Shell and Volume You have to specify the part and various properties of the element ANSYS ICEM CFD 12 1 2009 SAS IP Inc All rights reserved Contains proprietary and confidential 4 information of ANSYS Inc and its subsidiaries and affiliates 9 50 ANSYS ICEM CFD 12 1 2009 SAS IP Inc All rights reserved Contains proprietary and confidential information of ANSYS Inc and its subsidiaries and affiliates Constraints Here you can define the constraints on different entities such as points curves surfaces or subsets and define other options like Contact definition Velocity and Rigid Wall Create Constraint Displacement This option allows you to apply a directional or rotational constraint on a an entity in any direction Define Contact This option allows you to define contacts by Automatic Detection or Manual Definition Define Single Surface Contact This is mainly used for LS Dyna Solver where you can pick the contact surface Define Initial Veloci
9. measures the number of elements that belong within each quality sub range For descriptions of all the quality metrics refer to the Edit Mesh Display Mesh Quality section in the Help Manual Advanced Options for Smoothing Mesh Prism Warpage Ratio Prisms are smoothed based on a balance between prism warpage and prism aspect ratio Values from 0 01 to 0 50 favor improving the prism aspect ratio while those from 0 50 to 0 99 favor improving prism warpage A value of 0 5 favors neither The farther the value is from 0 5 the greater the effect Stay on geometry The default is when a grid is smoothed the nodes are restricted to the geometry surface curves and points and can only be moved along the geometrical entities to obtain a better mesh Violate Geometry Enabling this option allows the smoothing operation to yield a higher quality mesh by violating the constraints of the geometry The nodes can be moved off of the geometry to obtain better mesh quality as long as the movement remains within the absolute distance specified Relative Tolerance This option works in the similar fashion as Violate Geometry except that the distance is relative here Allow refinement If the quality of the mesh cannot be improved through normal algebraic smoothing the Allow refinement option will allow the smoother to automatically subdivide elements to obtain further improvement After smoothing with Allow refinement enabled it may be necessary to
10. object oriented unstructured meshing tech nology With no tedious up front triangular surface meshing required to provide well balanced initial meshes ANSYS ICEM CFD Tetra works directly from the CAD surfaces and fills the volume with tetrahedral elements using the Octree approach A powerful smoothing algorithm provides the element quality Options are available to automatically refine and coarsen the mesh both on geometry and within the volume A Delaunay algorithm is also included to create tetras from an existing surface mesh and also to give a smoother transition in the volume element size Hexa The ANSYS ICEM CFD Hexa mesher is a semi automated meshing module which allows rapid generation of multi block structured or unstructured hexahedral volume meshes ANSYS ICEM CFD Hexa represents a new approach to grid generation where the operations most often performed by experts are automated and made available at the touch of a button Blocks can be built and interactively adjusted to the under lying CAD geometry This blocking can be used as a template for other similar geometries for full para ANSYS ICEM CFD 12 1 2009 SAS IP Inc All rights reserved Contains proprietary and confidential information of ANSYS Inc and its subsidiaries and affiliates 3 Introduction to ANSYS ICEM CFD metric capabilities Complex topologies such as internal or external O grids can also be generated automatically Prism ANSYS ICEM CFD Prism generat
11. smooth further with the option dis abled The goal is to reduce the number of elements that are attached to one vertex by refinement in problem regions Laplace smoothing This option will solve the Laplace equation which will generally yield a more uniformly spaced mesh Note This can sometimes lead to a lower determinant quality of the prisms Also this option works only for the triangular surface mesh Allow node merging This option will collapse and remove the worst tetra and prism elements when smoothing in order to obtain a higher quality mesh This is enabled by default and is often very useful in improving the grid quality Not just worst 196 This option will smooth all of the geometry s elements to the assigned quality specified under Up to quality not just focus on the worst 196 of the mesh Typically when a mesh is smoothed the smoother concentrates on improving the worst regions this option will allow the smoother to continue smoothing beyond the worst regions until the desired quality is obtained ANSYS ICEM CFD 12 1 2009 SAS IP Inc All rights reserved Contains proprietary and confidential information of ANSYS Inc and its subsidiaries and affiliates 31 Tetra Meshing Surface fitting This option will smooth mesh keeping the nodes and the new mesh restricted along the surface of the geometry Only Hexa models will utilize this option Ignore PrePoints This option will allow the smoother to atte
12. the computational mesh generation postprocessing and mesh optimization tools available in ANSYS ICEM CFD allowing users to operate in their native CAD systems ANSYS ICEM CFD currently supports Direct CAD Interfaces for CATIA I deas Pro E and Unigraphics The ANSYS ICEM CFD environment can combine CAD surface geometry and triangulated surface data into a single geometry database tetin file using the geometry interfaces All geometry entities including surfaces curves and points are tagged or associated to a grouping called a part With this part association you can enable or disable all entities within the parts visualize them with a different color assign mesh sizes on all entities within the part and apply different boundary conditions by part Although most of the meshing modules within ANSYS ICEM CFD allow minor gaps and holes in the geometry in some cases it is necessary to find and close large gaps and holes without returning to the original CAD software ANSYS ICEM CFD provides tools for such operations on either CAD or triangulated surfaces Finally curves and points can be automatically created to capture certain key features in the geometry These curves and points will act as constraints for the mesher forcing nodes and edges of the elements to lie along them and thus capturing the feature Creating the Mesh The meshing modules available include the following Tetra The ANSYS ICEM CFD Tetra mesher takes full advantage of
13. use variables in the replay script as a means to parametrize edge parameters An example of the use of variables in a replay script is as follows variables set n 10 set hl 0 01 set rl 1 2 ANSYS ICEM CFD 12 1 2009 SAS IP Inc All rights reserved Contains proprietary and confidential information of ANSYS Inc and its subsidiaries and affiliates 45 Hexa ic load tetin myfile tin ic hex surface blocking inherited swept min edge 0 0 ic geo new family SOLID ic hex twod to threed SOLID swept ic hex set mesh 19 18 n n hl h1 h2rel 0 0 rl r1 r2 2 Imax 0 default unlocked ic hex create mesh SURFS SOLID proj 2 dim to mesh 3 ic hex write file hex uns SURFS SOLID proj 2 dim to mesh 3 family boco family boco fbc ic uns load hex uns 3 0 2 The variables for the edge parameters are set at the top of the replay file Within the script the indicates a variable To parametrize the edge parameters you may update the variables at the top of the script and then rerun the script Periodicity Periodic definition may be applied to the model in Hexa The Periodic nodes function which is found under Blocking Periodic nodes plays a key role in properly analyzing rotating machinery applications for example Typically you will model only a section of the rotating machinery as well as implement symmetry in order to minimize the model size By specifying a periodic relationship between the inflow and outflow boundaries t
14. yield quality meshes Generation of multi block structured unstructured and super domain meshes Ability to specify periodic definitions Extensive replay functionality with no user interaction for parametric studies ANSYS ICEM CFD 12 1 2009 SAS IP Inc All rights reserved Contains proprietary and confidential 42 information of ANSYS Inc and its subsidiaries and affiliates Edge Meshing Parameters Extensive selection of mesh bunching laws including the ability to graphically add delete modify control points defining the graph of the mesh bunching functions Link bunching relationships between block edges to automate bunching task Topology operations such as translate rotate mirror and scaling to simplify generation of the topology model e Automatic conversion of 3D volume block topology to 3D surface mesh topology e Automatic conversion of 2D block topology to 3D block topology Block face extrusion to create extended 3D block topology Multiple projection options for initial or final mesh computation Quality checks for determinant internal angle and volume of the meshes Domain renumbering of the block topology Output block definition to reduce the number of multi block structured output mesh files Block orientation and origin modification options Automatic O grid generation Generating O grids is a very powerful and quick technique used to achieve a quality mesh This process would not
15. Generation Steps The steps involved in generating a Tetra mesh are e Repairing cleaning up the geometry Specifying geometry details Specifying sizes on surfaces curves Meshing inside small angles or in small gaps between objects Desired mesh region Computing the mesh Checking the mesh for errors Editing the mesh to correct any errors Smoothing the mesh to improve quality The mesh is then ready to apply loads boundary conditions etc and for writing to the desired solver ANSYS ICEM CFD 12 1 2009 SAS IP Inc All rights reserved Contains proprietary and confidential 22 information of ANSYS Inc and its subsidiaries and affiliates Geometry Details Required Repairing the Geometry Refer to the CAD Repair section Geometry Details Required In addition to a closed set of surfaces the Tetra mesher requires curves and points where hard features hard angles corners are to be captured in the mesh Figure Curves and Points Representing Sharp Edges and Corners p 23 shows a set of curves and points representing hard features of the geometry Figure Curves and Points Representing Sharp Edges and Corners Figure Mesh with Curves and Points p 23 shows the resultant surface mesh if the curves and points are preserved in the geometry Mesh nodes are forced to lie along the curves and points to capture the hard features of the geometry Figure Mesh with Curves and Points Figure Mesh Withou
16. If no volume parts are selected it will assume that you want to grow prisms into all volumes bordering the prism surfaces If you select specific volume parts then prism will only be grown into those volumes After each layer is extruded smoothing is done according to the global settings The layers are grown one at a time This continues until all the requested layers are grown You can add prisms to exiting layers or you can subdivide and redistribute layers at a later date You can save time by growing only a few thicker layers and then subdividing them into many layers The smoothing is the most time consuming part so for simple configurations it may be best to turn off all smoothing but grow all the layers one at a time This allows you to take advantage of the variable height feature There are two ways to generate prism mesh Compute Mesh gt Prism Mesh This option is used to grow prism layers next to wall geometries You can define the local initial height growth ratio and number of layers at Mesh Global Mesh Setup Global Prism Settings This option can create prisms from existing volume or surface mesh ANSYS ICEM CFD 12 1 2009 SAS IP Inc All rights reserved Contains proprietary and confidential information of ANSYS Inc and its subsidiaries and affiliates 33 Prism Mesh Note If the existing volume mesh is tet hexa mesh on the hexa side the prisms will be added within the first hexa layer Compute M
17. M CFD 12 1 2009 SAS IP Inc All rights reserved Contains proprietary and confidential 56 information of ANSYS Inc and its subsidiaries and affiliates Temperature Consistent Load at Node 1 L1 Consistent Load at Node 5 L5 Consistent Load at Node 9 L9 Upon integration we get the following values L1 p L4 7 2 12 N d d 4p 36 L5 p 3 1 2 12 7 N d d 4p 9 L9 p 3 1 7 2 12 N d d 16p 9 Now F 4p Putting this value in the above equation we get the consistent Nodal Force as L1 F 36 L5 F 9 L9 4F 9 By symmetry Consistent Nodal Force on Node 1 2 3 amp 4 are equal By symmetry Consistent Nodal Force on Node 5 6 7 amp 8 are equal Now Total Force 4 L1 4 L5 L9 F 9 4F 9 4F 9 F Note The same method is employed for calculating the Consistent Nodal Force on the QUAD8 element which gives correct results Force Using this option you can apply force or moments on entities in all three directions Forces can be applied by two different options The Uniform option applies the force uniformly For curves this means that the nodes attached to the curve will have the same force applied to them The Total option means that the force gets distributed among all the nodes of the selected entities as per FEA concepts Pressure You can apply pressure loads to surfaces subsets or parts Temperature This option allows you to apply temperature to points curves surfaces bodies and subsets
18. T L3 LT L3 y O 5 FT L4 LT 0 5 FT LA4ILT L4 The formulation for a Linear Element is as follows Point 0 FO 0 5 FT L1 LT Point 1 F1 0 5 FT L1 LT 0 5 FT L2 LT Point 2 F2 0 5 FT L2 LT 0 5 FT L3 LT Point 3 F3 0 5 FT L3 LT 0 5 FT L4 LT Point 4 F4 0 5 FT L4 LT The general formula is Fi Sum FT L attached element LT 1 number of nodes per element If you sum up FO F1 F2 F3 F4 then the resultant comes to be FT It also satisfies the FEA concepts The same force is applied on the Quadratic Element shown in Figure Quadratic Element Nodes posi tion p 55 54 ANSYS ICEM CFD 12 1 2009 SAS IP Inc All rights reserved Contains proprietary and confidential information of ANSYS Inc and its subsidiaries and affiliates Figure Quadratic Element Nodes position 0 1 2 m1 m2 m3 3 m4 4 e 9 9 90 9 o e L1 L2 L3 LA m1 m2 m3 md4 are mid side nodes of Element 1 2 3 4 The Load distribution as per the FEA concept on the Quadratic elements is shown in Figure Load Distribution as per the FEA concepts p 55 Figure Load Distribution as per the FEA concepts 1 6 FT L1 LT 4 1 6 FT L1 LT m1 0 L1 1 1 69 FT L2 LT B 1 6 FT L2 LT m2 E L2 x ty FT C3 LT c 1 6 FT L3 LT 4 d o 9 06 A 2 3 FT LI LT a B 2 3 FT L2 LT 1 6 FT L4 LT p 1 6 FT L4 LT C 2 3 FT L3 LT D 2 3 F
19. T L4 LT m4 L4 The formulation of Total Force at the side nodes is as follows Point 0 FOq 1 6 FT L1 LT Point 1 F1q 1 6 FT L1 LT 1 6 FT L2 LT Point 2 F2q 1 6 FT L2 LT 1 6 FT L3 LT Point 3 F3q 1 6 FT L3 LT 1 6 FT L4 LT Point 4 Faq 1 6 FT L4 LT ANSYS ICEM CFD 12 1 2009 SAS IP Inc All rights reserved Contains proprietary and confidential information of ANSYS Inc and its subsidiaries and affiliates 55 Loads But the formulation of mid side node is Point m1 Fm1 2 3 FT L1 LT Point m2 Fm2 2 3 FT L2 LT Point m3 Fm3 2 3 FT L3 LT Point m4 Fm4 2 3 FT L4 LT As in the previous case of Linear Element the total Force of Quadratic element is Frotat FOq F1q F2q F3q F4q Fm1 Fm2 Fm3 Fm4 which yields Fro 4i FT QUAD 9 Consistent Nodal Load Distributions The Nine Node two dimension Lagrange QUAD 9 Element is shown in Figure QUAD9 Element p 56 Figure QUAD9 Element a N The Shape function for the Corner Node N 2 1 4 1 1 The Shape function for the Mid Side Node N5 1 2 2 1 27 2 1 The Shape function for the Middle Node No 1 22 1 27 Suppose a Force F is uniformly distributed over the whole Area Then the pressure is p F 4 Because in coordinate system the Area of the rectangle is 4 To Find the Consistent Load ANSYS ICE
20. airinad thiexGeom BEEV moises Decet gri veu ka Ra cats Orta tp aee pe run rd giten qv multe d m Fa uy ERR clam 23 Geometry Details R quired condo i qus Gee rt a en de e pud SEV aot uq M dd i uas MEAN RN gri eR tanen 23 Sizes ohn Surfaces ANG CURVES d src tesi nes levure dresden Ae IES EEEa op ae ey aal lo edipi 24 Meshing Inside Small Angles or in Small Gaps Between Objects seeeeeeenn 24 Desired Mesh REGION is re in ro rni b y cre HERR DC ERN TER tad VER aaa vc Ere rell ved t a a N 24 The Octree MESH Method MUNERE E EE 25 Iraportant Features In Tetra oso cree i tete Srt a eer na ep e nop eee ape EN Pa RET gar e eese v EE 28 Curvature Proximity Based Refinement cccsssescesesssrceesessesceseesseeeeseeseeseesenseeeessesseeeeseeseneeesenea 28 Tetrahedral Mesh SIootBel sse o Sarees enirn pta Rega tpa yoke leo euv sep pce pr e E gu end AS RAS 28 Tetrabedrab MESH COaFSBHTOR ih east sv it orat osa ga rir scit rea dus iia m doeet p d red goa 28 Triangular Surface Mesh Smoother ioi us c ote npa eni Fuente POR Ea Rl er a EF Ra vn la ER Haa 29 Triangular Surface Mesh Coarsener suci o e RR EC EE MAR YEN PAM AP SY ERU MEER sss RARRN TE PANT Ye ARR ad 29 Triangular Surface Editing TOS sussen dm eh drehen rior hp c EP Versos ta aioe de drin duni 29 Check MSS este i eod os MU pedet rais rd s Dec Plena deu PER a ec ite et ad uie UP 29 SmoothiMesh Globally iisioiho ve ipee e ps n ovp lvo o Lev a ave te ut tie asa wore 29 Q
21. ally scan the surface mesh Look for any surface discrepancies or sharp tent like structures in the mesh Make sure part associations are correct Look for a few elements of one part scattered among another part Extruding from a few isolated elements will likely crash the prism mesher Modify part assignments of such elements Use the Smoothing Options for Tetra and Tri surface mesh under Mesh gt Prism before creating prism mesh Laplace Triangle Quality type is typically best for eventual prism quality ANSYS ICEM CFD 12 1 2009 SAS IP Inc All rights reserved Contains proprietary and confidential 34 information of ANSYS Inc and its subsidiaries and affiliates Smoothing Tetra Prism Mesh Smoothing Tetra Prism Mesh First smooth the tetra and tri elements set PENTA 6 to Freeze Once the tetra and tri elements are as smooth as possible then smooth all elements at the same time including PENTA 6 Decrease the Up to quality value so that the prism elements are not distorted too much ANSYS ICEM CFD 12 1 2009 SAS IP Inc All rights reserved Contains proprietary and confidential information of ANSYS Inc and its subsidiaries and affiliates 35 36 ANSYS ICEM CFD 12 1 2009 SAS IP Inc All rights reserved Contains proprietary and confidential information of ANSYS Inc and its subsidiaries and affiliates Hexa Hexa is a 3 D object based semi automatic multi block structured a
22. asses through the selected block faces In Figure the Add Face option was used on the right most block to add the bottom face on the block prior to generating the O grid Another important feature of the automatic O grid is the ability to re scale the O grid after generation When the O grid is generated the size of the O grid is scaled based upon a factor in the Blocking O grid parameter window The Re scale O grid option allows you to re scale the previously generated O grid The blocks may also be modified by moving the vertices of the blocks and by defining specific relationships between the faces edges and vertices to the geometry Most Important Features of Hexa Hexa has emerged as the quickest and most comprehensive software for generating large highly accurate 3D geometry based hexahedral meshes Now in the latest version of Hexa it is also possible to generate 3D surface meshes with the same speed and flexibility e CAD and projection based hexahedral mesh generation Easy manipulation of the 3D object based topology model Modern GUI and software architecture with the latest hexahedral mesh technology Extensive solver interface library with over 100 different supported interfaces e Automatic O grid generation and O grid re scaling Geometry based mesh size and boundary condition definition Mesh refinement to provide adequate mesh size in areas of high or low gradients Smoothing relaxation algorithms to quickly
23. ation may be used disclosed transferred or copied only in accordance with the terms and conditions of that software license agreement ANSYS Inc is certified to ISO 9001 2008 U S Government Rights For U S Government users except as specifically granted by the ANSYS Inc software license agreement the use du plication or disclosure by the United States Government is subject to restrictions stated in the ANSYS Inc software license agreement and FAR 12 212 for non DOD licenses Third Party Software See the legal information in the product help files for the complete Legal Notice for ANSYS proprietary software and third party software If you are unable to access the Legal Notice please contact ANSYS Inc Published in the U S A Table of Contents Introduction to ANSYS ICEM CFD rerit eorr esa rx HERE nro EVER e rati Vere PY TRY EN Er dA p RESERVE RU RM HER Rud 1 OVSIall Processus nnn oa tet Ond oeuf Dun net fie e Par ado Eos rrev e aa tci bf dud No te fir 1 Opening Creating a ProJect eees eaten doe paese e pena na aaa gana eara gan TRE AERA E EE E ESS 2 Creating Manipulating the Geometry iii ees rh re ei ia Rn Ye uendere e EN EYA Te EYE Oen Ra e luu 3 Creating the GS IN erc 3 Checki ng Editing the MOS uae sna red raairid reei a e aia RP M nta aor aida 4 Generating the Input for the Solver os cararanianintain er Ek guten dL SR AUR CERTE A Tue COLERE Ven E EAS UR Cp 5 POSUPIOCESSING sicests DE DR 5 T
24. aw Uniform Hyperbolic e Poisson e Curvature ANSYS ICEM CFD 12 1 2009 SAS IP Inc All rights reserved Contains proprietary and confidential 4 information of ANSYS Inc and its subsidiaries and affiliates 3 Hexa Geometric 1 Geometric 2 Exponential 1 Exponential 2 Bi Exponential Linear Spline You may modify these existing laws by applying pre defined edge meshing functions accessible through the Meshing Edge Params Graphs option in Hexa This option yields these possible functions Constant Ramp Scurve Parabola Middle Parabola Ends e Exponential Gaussian Linear Spline Note By selecting the Graphs option you may add delete modify the control points governing the function describing the edge parameter settings Additional tools such as Linked Bunching and the multiple Copy buttons provide you with the ability to quickly apply the specified edge bunching parameters to the entire model Smoothing Techniques In Hexa both the block topology and the mesh may be smoothed to improve the overall block mesh quality either in a certain region or for the entire model The block topology may be smoothed to improve the block shape prior to mesh generation This reduces the time required for development of the block to pology model The geometry and its associative faces edges and points are all constraints when smoothing the block to pology model Once t
25. d affiliates Using the Automatic O grid Figure Hexa Block Types Mapped Structured i j k are mapped i jare mapped k im 1s Free Unstructured All edges are All edges are free free from mapping from mapping Split The Split function which divides the selected block interactively may be applied across the entire block or to an individual face or edge of a block by using the Split face or Split edge options respectively Blocks may be isolated using the Index control Merge The Merge function works similar to split blocks one can either merge the whole block or merge only a face or an edge of the block While some models require a high degree of blocking skill to generate the block topology the block topology tools in Hexa allow you to quickly become proficient in generating a complex block model Using the Automatic O grid The O grid creation capability is simply the modification of a single block or blocks to a 5 sub block topology as shown below There are several variations of the basic O grid generation technique and the O grid shown below is created entirely inside the selected block Figure Initial block block with O Grid O Grid with include a face ANSYS ICEM CFD 12 1 2009 SAS IP Inc All rights reserved Contains proprietary and confidential information of ANSYS Inc and its subsidiaries and affiliates 41 Using the Add face option an O grid may also be created such that the O grid p
26. d coarsening Tetra Mesh Generation The Tetra mesher is suitable for complex geometries and offers several advantages including Rapid model setup Mesh independent of underlying surface topology No surface mesh necessary Generation of mesh directly from CAD or STL surfaces Definition of element size on CAD or STL surfaces Control over element size inside a volume Nodes and edges of tetrahedra are matched to prescribed points and curves Curvature Proximity Based Refinement automatically determines tetrahedra size for individual geometry features Volume and surface mesh smoothing merging nodes and swapping edges Tetrahedral mesh can be merged into another tetra hexa or hybrid mesh and then can be smoothed Coarsening of individual material domains Enforcement of mesh periodicity both rotational and translational Surface mesh editing and diagnostic tools Local adaptive mesh refinement and coarsening One consistent mesh for multiple materials Fast algorithm 7500 elements second Automatic detection of holes and easy way to repair the mesh For more details go to Run Tetra The Octree Approach ANSYS ICEM CFD 12 1 2009 SAS IP Inc All rights reserved Contains proprietary and confidential information of ANSYS Inc and its subsidiaries and affiliates 21 Tetra Meshing Input to Tetra The following are possible inputs to the Tetra mesher Sets of B Spline curves and tr
27. d have the two sets of curves within some tolerance for this option to work Figure Geometry With Mismatched Edges ANSYS ICEM CFD 12 1 2009 SAS IP Inc All rights reserved Contains proprietary and confidential 18 information of ANSYS Inc and its subsidiaries and affiliates Match in Stitch Match Edges Figure Geometry After Using the Match Edges Option ANSYS ICEM CFD 12 1 2009 SAS IP Inc All rights reserved Contains proprietary and confidential information of ANSYS Inc and its subsidiaries and affiliates 19 20 ANSYS ICEM CFD 12 1 2009 SAS IP Inc All rights reserved Contains proprietary and confidential information of ANSYS Inc and its subsidiaries and affiliates Tetra Meshing Automated to the point that you have only to select the geometry to be meshed the Tetra mesher generates tetrahedral meshes directly from the CAD geometry or STL data without requiring an initial triangular surface mesh Introduction Tetra Generation Steps Important Features in Tetra Introduction The Tetra mesher can use different meshing algorithms to fill the volume with tetrahedral elements and to generate a surface mesh on the object surfaces You can define prescribed curves and points to determine the positions of edges and vertices in the mesh For improved element quality the Tetra mesher incorporates a powerful smoothing algorithm as well as tools for local adaptive mesh refinement an
28. d tolerance gaps or missing surfaces During the Tetra process any leakage path indicating a hole or gap in the model will be indicated The problem can either be corrected on a mesh level or the geometry in that vicinity can be repaired and the meshing process repeated For further information on the process of interactively closing holes see the section Tetra Tetra Generation Steps Useful Region of Mesh For more information on CAD Repair topics please go to this page Close Holes You can use the Close Holes option if the hole is bounded by more than one surface For example in Fig ure Hole Bounded by Multiple Surfaces p 15 the yellow curves represent the boundary of the hole It is clear that this hole is bounded by more than one surface Figure Hole Bounded by Multiple Surfaces Figure Closed Hole p 16 shows the geometry after the Close Holes operation is completed A new surface is created to close the hole ANSYS ICEM CFD 12 1 2009 SAS IP Inc All rights reserved Contains proprietary and confidential information of ANSYS Inc and its subsidiaries and affiliates 15 CAD Repair Figure Closed Hole Remove Holes You can use the Remove Holes option if the hole lies entirely within a single surface such as a trimmed surface For example in Figure Hole Within a Single Surface p 16 the two yellow curve loops represent the boundaries of the holes which lie entirely in one surface
29. d up with geometry curvature Patch based shell meshing Patch Dependent Uses a series of loops which are automatically defined by the boundaries of surfaces and or a series of curves This method gives the best quad dominant quality and capturing of surface details Patch independent shell meshing Patch Independent Uses the Octree method This is the best and most robust method for unclean geometry Shrinkwrap Used for quick generation of mesh As it is used as the preview of the mesh hard features are not captured Checking Editing the Mesh The mesh editing tools in ANSYS ICEM CFD allow you to diagnose and fix problems in the mesh You can also improve the mesh quality A number of manual and automatic tools are available for operations such as conversion of element types refining or coarsening the mesh smoothing the mesh etc The process typically involves the following 1 Check the mesh for problems such as holes gaps overlapping elements using the diagnostic checks available Fix the problems using the appropriate automatic or manual repair methods 2 Checkthe elements for bad quality and use smoothing to improve the mesh quality 3 Ifthe mesh quality is poor it may be appropriate to fix the geometry instead or recreate the mesh using more appropriate size parameters or a different meshing method ANSYS ICEM CFD 12 1 2009 SAS IP Inc All rights reserved Contains proprietary and confidential 4 i
30. e thus allowing you to return to previous block topologies Additionally at any point in this process you can generate the mesh with various projection schemes such as full face projection edge projection point projection or no projection at all Note In the case of no projection the mesh will be generated on the faces of the block model and may be used to quickly determine if the current blocking strategy is adequate or if it must be modified The Hexa Database The Hexa database contains both geometry and block topology data each containing several sub entities The Geometric Data Entities Points x y z point definition Curves trimmed or untrimmed NURBS curves ANSYS ICEM CFD 12 1 2009 SAS IP Inc All rights reserved Contains proprietary and confidential 38 information of ANSYS Inc and its subsidiaries and affiliates Blocking Strategy Surfaces NURBS surfaces trimmed NURBS surfaces The Block Topologic Data Entities Vertices corner points of blocks of which there are at least eight that define a block Edges a face has four edges and a block twelve Faces six faces make up a block Blocks volume made up of vertices edges and faces Intelligent Geometry in Hexa Using ANSYS ICEM CFD s Direct CAD Interfaces which maintain the parametric description of the geometry throughout the CAD model and the grid generation process hexahedral grids can be easily remeshed on the modified ge
31. e Scale Factor is assigned a value of 0 the Tetra mesher will not run Meshing Inside Small Angles or in Small Gaps Between Objects Examine the regions between two surfaces or curves that are very close together or that meet at a small angle This would also apply if the region outside the geometry has small angles If the local tetra sizes are not small enough so that at least 1 or 2 elements would fit through the thickness you should define thin cuts This option is in the Mesh Global Mesh Setup Volume Meshing Parameters section To define a thin cut the two surfaces have to be in different Parts If the surfaces meet the curve at the intersection of the surfaces will need to be in a different part If the tetra sizes are larger or approximately the same size as the gap between the surfaces or curves the surface mesh could have a tendency to jump the gap thus creating non manifold vertices These non manifold vertices would be created during the meshing process The Tetra mesher automatically attempts to close all holes in a model Since the gap may be confused as a hole you should either define a thin cut in order to establish that the gap is not a hole or make the mesh size small enough so that it won t close the gap when the meshing is performed A hole is usually considered a space that is greater than 2 or 3 elements in thickness Desired Mesh Region During the process of finding the bounding surfaces to close the volume mes
32. e sub categories are enabled and some disabled Each category can be expanded by se lecting the symbol to reveal the sub categories Select performed only on the entities shown the tree is an important feature to use when isolating the particular entities to be modified Clicking on a particular category or type using the right mouse button will reveal several display and modification options to collapse the tree Since some functions are ANSYS ICEM CFD 12 1 2009 SAS IP Inc All rights reserved Contains proprietary and confidential information of ANSYS Inc and its subsidiaries and affiliates GUI Components The Message Window Figure The Message Window Updating histogram al D gt 0 05 0 0 000 0 05 gt 0 1 0 0 000 0 1 gt 0 15 0 0 000 0 15 gt 0 2 0 0 000 0 2 gt 0 25 0 0 000 0 25 gt 0 3 0 0 000 0 3 gt 0 35 0 0 000 0 35 gt 0 4 0 0 000 0 4 gt 0 45 0 0 000 0 45 gt 0 5 0 0 000 0 5 gt 0 55 121 0 579 0 55 gt 0 6 132 0 632 0 6 gt 0 65 151 0 723 0 65 gt 0 7 407 1 949 0 7 gt 0 75 1181 5 655 0 75 gt 0 8 1704 8 160 0 8 gt 0 85 3169 15 175 0 85 gt 0 3 5224 25 016 0 9 gt 0 95 6918 33 127 0 95 gt 1 1876 8 983 z Yv Log Save Dear The Message Window contains all the messages that ANSYS ICEM CFD writes out to keep the user informed of internal p
33. eite naa exe uoto taxe un aide to E En 61 Workbench Integration Lean e reste e d e ord sitne ere iae eee get 63 ANSYS ICEM CFD 12 1 2009 SAS IP Inc All rights reserved Contains proprietary and confidential information of ANSYS Inc and its subsidiaries and affiliates V vi ANSYS ICEM CFD 12 1 2009 SAS IP Inc All rights reserved Contains proprietary and confidential information of ANSYS Inc and its subsidiaries and affiliates Introduction to ANSYS ICEM CFD ANSYS ICEM CFD provides advanced geometry acquisition mesh generation mesh optimization and post processing tools to meet the requirement for integrated mesh generation and post processing tools for today s sophisticated analyses Maintaining a close relationship with the geometry during mesh generation and post processing ANSYS ICEM CFD is used especially in engineering applications such as computational fluid dynamics and structural analysis ANSYS ICEM CFD s mesh generation tools offer the capability to parametrically create meshes from geometry in numerous formats e Multiblock structured Unstructured hexahedral Unstructured tetrahedral Cartesian with H grid refinement Hybrid meshes comprising hexahedral tetrahedral pyramidal and or prismatic elements Quadrilateral and triangular surface meshes ANSYS ICEM CFD provides a direct link between geometry and analysis In ANSYS ICEM CFD geometry can be input from just abou
34. elds indicate the entities selected for a particular operation Click the button adjacent to the selection field to invoke the selection mode The selection toolbar associated with the operation will appear After confirming the selections the selected items will be listed in the selection field 10 ANSYS ICEM CFD 12 1 2009 SAS IP Inc All rights reserved Contains proprietary and confidential information of ANSYS Inc and its subsidiaries and affiliates Using the Help System Selection Toolbar Select geometry The selection toolbars contain some tools common to all select operations and some toggles for filtering entities for selection Some controls are linked to the hotkeys available in the select mode Using the Help System The product online help system provides easy access to the program documentation The entire User s Manual Help Manual and other documentation modules are available through the graphical user interface Click Help on the main menu and select the appropriate option from the menu Figure Help Menu Options Help Help Topics Tutorial Manual User Manual Programmer s Guide Installation amp Licensing Guide What s New Legal Notices Show Customer Number About ANSYS ICEM CFD ANSYS ICEM CFD 12 1 2009 SAS IP Inc All rights reserved Contains proprietary and confidential information of ANSYS Inc and its subsidiaries and affiliates 11 Introduction to ANSYS ICEM CFD On
35. ertices of these edges also blue can be moved by se lecting the edge just before it and can be dragged on that edge Green Edges and Vertices These edges and the associated vertices are being projected to curves The vertices can only be moved on the curves to which it is being projected Red Vertices These vertices are projected to prescribed points Hexa Block Types When blocking a model it is important to note that the block type affects many operations within Hexa and the entire approach to mesh generation For example if you split a model with mapped blocks the split will propagate through faces that have a mapped relationship on the opposite side For free blocks a split will terminate at the free face Similarly if you set edge parameters on a mapped face edge opposite edges will have a similar number of nodes If however that edge is attached to a free face the number of nodes on the opposite side will not be adjusted Using this free mapped relationship you can shape the blocking and resulting mesh The ability to convert blocks from free to mapped or vice versa imposes constraints on the blocking and resulting mesh By imposing more constraints you can enforce a greater number of hexa elements while reducing the constraints can sometimes improve mesh transitioning ANSYS ICEM CFD 12 1 2009 SAS IP Inc All rights reserved Contains proprietary and confidential 40 information of ANSYS Inc and its subsidiaries an
36. es hybrid tetrahedral grids consisting of layers of prism elements near the boundary surfaces and tetrahedral elements in the interior for better modeling of near wall physics of the flow field Compared to pure tetrahedral grids this results in smaller analysis models better con vergence of the solution and better analysis results Hybrid Meshes The following types of hybrid meshes can be created Tetra and Hexa meshes can be united merged at a common interface in which a layer of pyramids is automatically created at a common interface to make the two mesh types conformal These meshes are suitable for models where it is preferred to have a structured hexa mesh in one part and is easier to create an unstructured tetra mesh in another more complex part Hexa Core meshes can be generated where the majority of the volume is filled with a Cartesian array of hexahedral elements essentially replacing the tetras This is connected to the remainder of a prism tetra hybrid by automatic creation of pyramids Hexa Core allows for reduction in number of elements for quicker solver run time and better convergence Shell Meshing ANSYS ICEM CFD provides a method for rapid generation of surface meshes quad and tri both 3D and 2D Mesh types can be All Tri Quad w one Tri Quad Dominant or All Quad The following methods are available Mapped based shell meshing Autoblock Internally uses a series of 2D blocks resulting in a mesh better line
37. esh Volume Mesh Create Prism Layers This option allows you to directly create tetra mesh with prisms next to wall geometries You can choose whether to create prism mesh from the geometry and or the surface mesh Note If many prism layers are created it is faster and can be more robust to create initial prism layers and then split them to create the total desired number of prism layers using Edit Mesh Split Mesh Split Prisms For more useful information on Prism Mesh please go to this page Prism Mesh Process The prism mesh process generates prism elements near boundary surfaces from tetrahedral or tri surface mesh This batch process creates prisms by extrusion of the surface mesh and the resulting prisms are made conformal with any existing tetrahedral volume mesh The prism mesh can be smoothed to yield the necessary quality Prism Mesh Preparation When generating prism mesh preparation is key It is easier to edit a tetra mesh than a tetra prism mesh Prism mesh can also be difficult to smooth so it will save time to start with good quality tetra or tri surface mesh Start with the best possible initial hybrid mesh quality Hybrid mesh is generally difficult to smooth Start with good Tetra or Tri surface mesh Choose prism options carefully Check aspect ratios quality Check and fix all diagnostics Single multiple edges Non manifold vertices and Duplicate elements will crash the prism mesher e Visu
38. etary and confidential information of ANSYS Inc and its subsidiaries and affiliates 59 60 ANSYS ICEM CFD 12 1 2009 SAS IP Inc All rights reserved Contains proprietary and confidential information of ANSYS Inc and its subsidiaries and affiliates Cart3D For FAQ on Cart3D including information on Cart3D batch commands and sixDOF batch commands please go to this page For other product information please go to this page ANSYS ICEM CFD 12 1 2009 SAS IP Inc All rights reserved Contains proprietary and confidential information of ANSYS Inc and its subsidiaries and affiliates 61 62 ANSYS ICEM CFD 12 1 2009 SAS IP Inc All rights reserved Contains proprietary and confidential information of ANSYS Inc and its subsidiaries and affiliates Workbench Integration Named Selections Named Selections created in Design Modeler can be imported into Advanced Meshing as either parts or subsets In Design Modeler make sure that the Named Selections option under the Default Geometry Options is checked To import all Named Selections leave the prefix field blank Then proceed with opening the project in Advanced Meshing In Advanced Meshing go to Settings gt Workbench Select the Named Selec tions as parts option or toggle it OFF to import the named selections as subsets ANSYS ICEM CFD 12 1 2009 SAS IP Inc All rights reserved Contains proprietary and confidential informa
39. h the mesher will determine if there are holes in the model If holes are found the Message window will display a message like Material point ORFN can reach material point LIVE You will be prompted with a dialog box saying Your geometry has a hole do you want to repair it A jagged line will display the leakage path from the ORFN part to the LIVE part The elements surrounding the hole will also be displayed To repair the hole select the single edges bounding it and the mesher will loft a surface mesh to close the hole Further holes would be flagged ANSYS ICEM CFD 12 1 2009 SAS IP Inc All rights reserved Contains proprietary and confidential 24 information of ANSYS Inc and its subsidiaries and affiliates The Octree Mesh Method and repaired in the same manner If there are many problem areas it may be better to repair the geometry or adjust the meshing parameters The Octree Mesh Method The Octree mesh method is based on the following spatial subdivision algorithm This algorithm ensures refinement of the mesh where necessary but maintains larger elements where possible allowing for faster computation Once the root tetrahedron which encloses the entire geometry has been initialized Tetra subdivides the root tetrahedron until all element size requirements are met Figure Geometry Input to Tetra At this point the Tetra mesher balances the mesh so that elements sharing an edge or face do not differ in
40. have been possible without the presence of O grids The O grid technique is utilized to model geometry when the you desire a circular or O type mesh either around a localized geometric feature or globally around an object Important Features of an O grid Generation of Orthogonal Mesh Lines at an Object Boundary The generation of the O grid is fully automatic and you simply select the blocks needed for O grid generation The O grid is then generated either inside or outside the selected blocks The O grid may be fully contained within its selected region or it may pass through any of the selected block faces Rescaling an O grid After Generation When the O grid is generated the size of the O grid is scaled based upon the Factor in the Blocking gt O grid parameter window You may modify the length of the O grid using the Blocking Re scale O grid option If a value that is less than 1 is assigned the resulting O grid will be smaller than the original If however a value is larger than 1 the resulting O grid will be larger Edge Meshing Parameters The edge meshing parameter task has been greatly automated by providing you with unlimited flexibility in specifying bunching requirements Assigning the edge meshing parameters occurs after the development of the block topology model This option is accessible by selecting Meshing Edge params You can use the following pre defined bunching laws or Meshing laws Default Bi Geometric L
41. he ANSYS ICEM CED GUI aic canner etg pred RD a QUCHPA Vra Kus dod eaten nadiceg ER dE eR ROS HR QUY eli eu EQ M fone 5 GUI Components x ee erect eter tere dee eae as te quete het een tet ce de T EE N 6 Madin Menu ettet rte re Rer nere e gta qure ae tessa te eer nate Pre vega ae taret ve verge ge unde 6 Buceo DT 7 FUnellori ab Sacasaci areis Quit d eudon tercio ut at Tra ia patna ride E tn Pauper dui 7 The Display Control TCS e oscura et e n RE erint Ru roba RU c Me a ded SU rs 8 The Message WIBOOW ace teer vena ei ep end gush ne aaa ER gor eu Cate Pa nba V dl ed edt 9 The Histogram WindOW adr E REUS RENE A REIR PER OR aa VE b SR womans DRAN TURF MENDA Gd ME 9 The Data Entry Zone DEZ 5 5 nte ear Soter eo e eee ege ee AIC Ede ee aed de 10 Using the Help SYSTEM dcs ug EH ERE On hr MRNA FOR MO p aC CY END Seu Ru RE UA f ERE Dude EC MR 11 GAD c r 15 Ger Malo T Y 15 Remove IOI cC E Ss 16 Fill Trim and Blend in Stitch Match Edges cccccccccessssssnteceeceeseesesnnneceeceeceeeesenaeeeeeeeesseeesnneeeeeeseeeeees 17 Mateh in Stiteh Match Edges cin an a aaeeea iaaa eneen aena ee ne ret Contatore amin TE a a K Fu E UP CHR ANS ERR E PRA RR 18 Tetra TLIJDLmeM T MEN EN 21 IVEROCUCTION et re Cr 21 Tetr Mesh Generator dac Vend ee eae e bo enia e px Ne ia a Golungo gen oe lea Ns gd 21 ajos uice T 22 Iu Ecrire 22 Rep
42. he block topology smoothing has been performed you may smooth the mesh after specifying the proper edge bunching parameters The quality criteria for smoothing are described in the Help Manual under Blocking Pre Mesh Quality ANSYS ICEM CFD 12 1 2009 SAS IP Inc All rights reserved Contains proprietary and confidential 44 information of ANSYS Inc and its subsidiaries and affiliates Using Variables in the Replay Script Refinement and Coarsening The refinement function which is found through Blocking Pre Mesh Params Refinement can be modified to achieve either a refined or a coarsened result The refinement coarsening may be applied in all three major directions simultaneously or they may be applied in just one major direction Refinement The refinement capability is used for solvers that accept non conformal node matching at the block boundaries The refinement capability is used to minimize the model size while achieving proper mesh definition in critical areas of high gradients Entering a scale factor greater than 1 will result in refinement Coarsening In areas of the model where the flow characteristics are such that a coarser mesh definition is adequate coarsening of the mesh may be appropriate to contain model size Entering a scale factor less than 1 will result in coarsening Replay Functionality Parametric changes made to model geometry are easily applied through the use of Hexa s replay functio
43. he particular specification may be applied to the model flow characteristics entering a boundary must be identical to the flow characteristics leaving a boundary Applying the Periodic Relationship The periodic relationship is applied to block faces and ensures that a node on the first boundary have two identical coordinates to the corresponding node on the second boundary You will be prompted to select corresponding vertices on the two faces in sequence When all vertices on both flow boundaries have been selected a full periodic relationship between the boundaries has been generated Pre Mesh Quality The pre mesh quality functions are accessible through Blocking Pre Mesh Quality Applying any of the quality checks will yield a histogram plot Some of the quality metrics are explained below Determining the Location of Elements By clicking on any of the histogram bars with the left button you may determine where in the model these elements are located The selected histogram bars will be highlighted by a change in color After selecting the bar s the Show button is pressed to highlight the elements in this range If the Solid option is enabled the elements marked in the histogram bars will be displayed with solid shading Determinant The Determinant check computes the deformation of the elements in the mesh by first calculating of the Jacobian of each hexahedron and then normalizing the determinant of the matrix A value of 1 rep
44. hing Num bars This represents the number of subdivisions within the range between the Min and the Max values The default Bars have widths of 0 05 Increasing the number of displayed bars however will decrease this width The Reset option will return all of the values back to the original parameters Show Click the left mouse button on any of the bars in the histogram and the color will change from green to pink Enabling Show will display the elements that fall within the selected range on the model in the main viewing window Solid Enabling this option will display the elements as solid rather than as the default grid represent ation You need to enable Show as well to activate this option Subset If you highlight bars from the histogram and enable Show the elements displayed in white color will be placed into a Subset The visibility of this subset is controlled by Subset in the Display Tree The Add select option allows you to add elements to an already established subset ANSYS ICEM CFD 12 1 2009 SAS IP Inc All rights reserved Contains proprietary and confidential 30 information of ANSYS Inc and its subsidiaries and affiliates Advanced Options for Smoothing Mesh Quality Metrics This option allows you to modify the histogram display The histogram displays the overall quality of the mesh The x axis measures the quality with 0 representing poor quality and 1 representing high quality The y axis
45. hing of that entity will be 4 35 14 0 units The Global Element Scale Factor can be any positive real number and it allows you to globally control the mesh size instead of changing the mesh parameters for different entities Display when enabled a reference mesh element will be displayed that corresponds to the specified element size The help system is organized into different documentation modules which are further organized in sections which are listed on the Contents tab Click the document icon or topic title next to each section to display its content in the right windowpane The Search tab allows you to view topics that contain certain words or phrases you specify When you execute a search all topics containing the search text display To go to that topic double click the topic To find out where you are in the help system click the Contents tab The highlighted entry in the table of contents indicates where the topic is The Search tab in the Windows Help includes several capabilities to assist you in narrowing down in formation returned in your searches Some of these capabilities are Using quotes to search for literal phrases Using Boolean operators AND OR NOT NEAR to precisely define search expressions ANSYS ICEM CFD 12 1 2009 SAS IP Inc All rights reserved Contains proprietary and confidential 12 information of ANSYS Inc and its subsidiaries and affiliates Online Help Interface
46. immed B Spline surfaces with prescribed points Triangular surface meshes as geometry definition Full partial surface meshes B Spline Curves and Surfaces When the input is a set of B Spline curves and surfaces with prescribed points the mesher approximates the surface and curves with triangles and edges respectively and then projects the vertices onto the prescribed points The B Spline curves allow the Tetra mesher to follow discontinuities in surfaces If no curves are specified at a surface boundary the Tetra mesher will mesh triangles freely over the surface edge Similarly prescribed points allow the mesher to recognize sharp corners in the geometry ANSYS ICEM CFD provides tools Build Topology to extract points and curves to define sharp features in the surface model Triangular Surface Meshes as Geometry Definition Prescribed curves and points can also be extracted from triangulated surface geometry This could be stere olithography STL data or a surface mesh converted to faceted geometry Though the nodes of the Tetra generated mesh will not exactly match the nodes of the given triangulated geometry they will follow the overall shape A geometry for meshing can contain both faceted and B Spline geometry Full Partial Surface Mesh Existing surface mesh for all or part of the geometry can be specified as input to the Tetra mesher The final mesh will then be consistent with and connected to the existing mesh nodes Tetra
47. its subsidiaries and affiliates 27 Tetra Meshing Figure Final Mesh after smoothing Important Features in Tetra The following sections describe important features of tetra meshing Curvature Proximity Based Refinement If the maximum tetrahedral size defined on a surface is larger than needed to resolve the feature you can employ Curvature Proximity Based Refinement to automatically subdivide the mesh to capture the feature The value specified is proportional to the global scale factor and is the smallest size to be achieved through automatic element subdivision Even with large sizes specified on the surfaces the features can be captured automatically The Curvature Proximity Based Refinement value is the minimum element size to be achieved via auto matic subdivision If the maximum size on a geometry entity is smaller than the Curvature Proximity Based Refinement value the Tetra mesher will still subdivide to meet that requested size The effect is a geometry based adaptation of the mesh Tetrahedral Mesh Smoother In smoothing the mesh the tetrahedral smoother calculates individual element quality based on the selection from the list of available criteria The smoother modifies the elements with quality below the specified Up to quality value Nodes can be moved and or merged edges are swapped and in some cases elements are deleted This operation is then repeated on the improved grid up to the specified number of ite
48. leted Individual triangles of the mesh can be subdivided or tagged with different names You can perform quality checks as well as local smoothing Diagnostic tools for surface meshes allow you to fill holes easily in the surface mesh Also there are tools for the detection of overlapping triangles and non manifold vertices as well as detection of single multiple edge and duplicate elements Check Mesh Check the validity of the mesh using Edit Mesh Check Mesh You can opt to use the Create subsets option for each of the problems so that they can be fixed later or can opt to use the Check fix each option to check and fix each one of them Using subset manipulation and mesh editing techniques you can diagnose the problem and resolve it through merging nodes splitting edges swapping edges delete create elements etc For ease of use when working with subsets it is usually helpful to add elements to the subset in order to see what is happening around the problem elements To do this right click on the Subset name in the Display tree and then add layers of elements to the subset It is also useful to display the element nodes and or display the elements slightly smaller than actual size Both of these options can be accessed by right clicking on Mesh in the Display Tree Keep in mind that after mesh editing the diagnostics should be re checked to verify that no mistakes were made There are several checks for Errors as well as Possible p
49. line Help Interface Figure The Online Help Interface E Documentation for ANSYS ICEM CFD 12 0 X c amp P Hide Back Print Options Contents s Search amp y Documentation for ANSYS ICEM CFD 5 Release Notes amp 3 Help Manual 59 Main Menu 5 Selection Options 59 Display Tree jj Geometry amp y Mesh amp Global Mesh Setup Global Mesh Size E G3 Shell Meshing Paramet gg Volume Meshing Paran m Prism Meshing Parame 8 Periodicity Set Up E Part Mesh Setup Surface Mesh Setup B Curve Mesh Setup E Create Mesh Density jg Define Connectors Mesh Curve 59 Compute Mesh Blocking Edit Mesh Properties Constraints G Loads 4 Solve Options a Output 5 Cart3D 59 Post Processing jg User Manual 5 Installation and Licensing Documentati CER Documentation for ANSYS ICEM CFD 12 0 Shell Meshing Parameters e Prev Next AN Help Manual Mesh Global Mesh S Global Mesh Setup 1 Global Mesh Size W The Global Mesh Size parameters affect meshers at the surface volume and inflation prism layer levels Global Element Scale Factor multiplies other mesh parameters to globally scale the model For a list of parameters affected by this scale factor please see the tables in Global Mesh Setup For example if the Max Element Size of a given entity is 4 units and the Global Element Scale Factor is 3 5 then the actual maximum element size used for mes
50. mpt to improve the mesh quality without being bound by the initial points of the geometry This option is similar to the Violate geometry option but works only for points located on the geometry This option is available only when there are hexahedral elements in the model Usually the best way to improve the quality of grids that cannot be smoothed above a certain level is to concentrate on the surface mesh near the bad elements and edit this surface mesh to improve the quality 32 ANSYS ICEM CFD 12 1 2009 SAS IP Inc All rights reserved Contains proprietary and confidential information of ANSYS Inc and its subsidiaries and affiliates Prism Mesh Tetra meshing is not efficient for capturing shear or boundary layer physics Prism mesh efficiently captures these effects near the surface while maintaining the ease and automation of Tetra mesh Prism has always been necessary for CFD customers but now that the option is more widely available many other branches of CAE have started using prisms to better resolve the physics perpendicular to the surfaces of their models With ANSYS ICEM CFD Prism and Tetra generation is automatic and intelligent The spacing of the prism layers to capture the Y for Navier Stokes mesh is the primary concern The rate of volume change between cells is also important Calculations are done between nodes or elements and Prism mesh gives you more elements perpendicular to the surface This efficien
51. n ality found in File Replay Scripts Changes in length width and height of specific geometry features are categorized as parametric changes These changes do not however affect the block topology Therefore the Replay function is capable of automatically generating a topologically similar block model that can be used for the parametric changes in geometry If any of the Direct CAD Interfaces are used all geometric parameter changes are performed in the native CAD system You can also use variables in the replay script to parametrize edge parameters Refer to Using Variables in the Replay Script p 45 for details Generating a Replay File The first step in generating a Replay file is to activate the recording of the commands needed to generate the initial block topology model All of the steps in the mesh development process are recorded including blocking mesh size edge meshing boundary condition definition and final mesh generation The next step in the process is to make the parametric change in the geometry and then replay the recorded file on the changed geometry All steps in the mesh generation process are automated from this point Advantage of the Replay Function With the Replay option you may analyze more geometry variations thus obtaining more information on the critical design parameters This can yield optimal design recommendations within the project time limits Using Variables in the Replay Script You can
52. n of internal walls In general there is no need to perform any individual face associations to underlying CAD geometry which further reduces the difficulty of mesh generation For more useful information on Hexa please go to this page Features of Hexa Some of the more advanced features of Hexa include O grids For very complex geometry Hexa automatically generates body fitted internal and external O grids to parametrically fit the block topology to the geometry to ensure good quality meshes Edge Meshing Parameters Hexa s edge meshing parameters offer unlimited flexibility in applying user specified bunching requirements Time Saving Methods Hexa provides time saving surface smoothing and volume relaxation algorithms on the generated mesh Mesh Quality Checking With a set of tools for mesh quality checking elements with undesirable skewness or angles may be displayed to highlight the block topology region where the individual blocks need to be adjusted ANSYS ICEM CFD 12 1 2009 SAS IP Inc All rights reserved Contains proprietary and confidential J information of ANSYS Inc and its subsidiaries and affiliates 3 Hexa Mesh Refinement Coarsening Refinement or coarsening of the mesh may be specified for any block region to allow a finer or coarser mesh definition in areas of high or low gradients respectively Replay Option Replay file functionality enables parametric block topology generation linked to parame
53. nd unstructured surface and volume mesher Introduction Hexa represents a new approach to hexahedral mesh generation The block topology model is generated directly on the underlying CAD geometry Within an easy to use interface those operations most often performed by experts are readily accessible through automated features There is access to two types of entities during the mesh generation process in Hexa block topology and geometry After interactively creating a 3 D block topology model equivalent to the geometry the block topology may be further refined through the splitting of edges faces and blocks In addition there are tools for moving the block vertices individually or in groups onto associated curves or CAD surfaces You may also associate specific block edges with important CAD curves to capture important geometric features in the mesh Moreover for models where you can take advantage of symmetry conditions topology transformations such as translate rotate mirror and scaling are available The simplified block topology concept allows rapid generation and manipulation of the block structure and ultimately rapid generation of the hexahedral meshes Hexa provides a projection based mesh generation environment where by default all block faces between different materials are projected to the closest CAD surfaces Block faces within the same material may also be associated to specific CAD surfaces to allow for definitio
54. ndo redo and display options They also include measurement and setup of local coordinate systems Function Tabs Figure Function Tabs Geometty Mesh Blocking Edit Mesh Properties Constraints Loads Solve Options Output Cart3D Post processing LS ed tnd ci ON sath 0Q0Q Q The Function Tabs allow you to access the main functionality for the entire grid generation process The function tabs include Geometry Mesh Blocking Edit Mesh Properties Constraints Loads Solve Options Output Cart3D and Post processing ANSYS ICEM CFD 12 1 2009 SAS IP Inc All rights reserved Contains proprietary and confidential information of ANSYS Inc and its subsidiaries and affiliates 7 Introduction to ANSYS ICEM CFD The Display Control Tree Figure The Display Control Tree Model 4 Geometry fi Subsets Points Curves Surfaces Bodies T Mesh amp Subsets Lines Shells Volumes Blocking Subsets O Vertices Edges Faces Blocks Pre Mesh H Topology a root CHA Parts I CURVES af CYLI af CYL2 I M IN I LIVE I M OUT af POINTS M SYM LO VORFN The Display Control tree also referred to as the Display tree along the upper left side of the screen allows control of the display by part geometric entity element type and user defined subsets The tree is organized by categories Each category can be enabled or disabled by selecting the check box If the check mark is faded some of th
55. nformation of ANSYS Inc and its subsidiaries and affiliates The ANSYS ICEM CFD GUI Generating the Input for the Solver ANSYS ICEM CFD includes output interfaces to various flow and structural solvers producing appropriately formatted files that contain complete mesh and boundary condition information After selecting the solver you can modify the solver parameters and write the necessary input files The list of supported solvers is available at the ANSYS ICEM CFD website Postprocessing ANSYS ICEM CFD allows you to view the solution results from different solvers The results file from various CFD and structural formats must first be loaded to make the postprocessing menu active You can visualize results using cut planes iso surfaces imported external surfaces streams animations calculate integrals and plot XY files The ANSYS ICEM CFD GUI The ANSYS ICEM CFD GUI offers a complete environment to create and edit computational grids The main menu is in the top left corner Below it are utility icons for more commonly used functions such as Save and Open as well as measure tools and view controls such as zoom extents Along the top right of the window are function tabs The function tabs are laid out from left to right in the order of a typical meshing process Clicking on a tab brings its action icons to the fore front Clicking on any of these icons will activate the associated Data Entry Zone DEZ The snapshot shows the Co
56. nvert Mesh Type DEZ which also has a selection toolbar associated with it The histogram is displayed in the lower right corner Simultaneously the text histogram is displayed in the message window The message window provides feedback and inform ation for most commands and also serves as a text entry point The upper left corner of the screen contains the Display tree which you can use to modify the display of entities modify properties and create subsets Note The default GUI style shown in Figure ANSYS ICEM CFD GUI Components p 6 is the Workbench style For more information about the GUI Style options refer to the Product Selection settings ANSYS ICEM CFD 12 1 2009 SAS IP Inc All rights reserved Contains proprietary and confidential information of ANSYS Inc and its subsidiaries and affiliates 5 Introduction to ANSYS ICEM CFD Figure ANSYS ICEM CFD GUI Components Utilities Selection Toolbar Main Menu Display Control Tree Function Tabs IKCEM FD 12 0 1 phere cube 2 dem Vicometty Meth Glocking Edt Meth Properties Constanta Lobds Solve Optons Output CD Post grocessing GY SFG Aras lt GHoVie pe ke Display Method tetra to 4 hes Eemeeis 0125015 0 00001 005 gt 01 0100003 002 005 000003 Selecting elements element CEU Te EE ENS ERT RET EET I Log Swel Cie 0 01 02 03 Q4 05 Q6 07 08 09 1 Data Entry Zone Message Window Histogram Window DEZ GUI Componen
57. ometry The geometry is selected in the CAD system and tagged with information made intelligent for grid gener ation such as boundary conditions and grid sizes and this intelligent geometry information is saved with the master geometry In Hexa by updating all entities with the update projection function blocking vertices projected to prescribed points in the geometry are automatically adapted to the parametric change and one can recalculate the mesh immediately Additionally with the use of its Replay functionality Hexa provides complete access to previous operations Unstructured and Multi block Structured Meshes The mesh output of Hexa can be either unstructured or multi block structured and need not be determined until after you have finished the whole meshing process when the output option is selected Unstructured Mesh Output The unstructured mesh output option will produce a single mesh output file where all common nodes on the block interfaces are merged independent of the number of blocks in the model Multi Block Structured Mesh Output Used for solvers that accept multi block structured meshes the multi block structured mesh output option will produce a mesh output file for every block in the topology model For example if the block model has 55 blocks there will be 55 output files created in the output directory Additionally without merging any of the nodes at the block interfaces the Output Block option allows y
58. oturitstefer m dear aucta tuto Dupsac didt vias dou dra otn tei a RA Doai Raa 51 Define Planar Rigid wall ot oett rtr ern RA Um Cram dere FIO ved ra t URP EE PE tuna COR RR ALL asad 51 Loads i eerie a PM ra CE OR b OR OR E PO Sb enu WARE des FE DAE OR DR e Ea NRO 53 ge Ra 57 PIeSSUEG ses deret ded eoo der eur edge E Mee date DO Sova Pee euo vue oe gos te neci ere eoo Ses eu edges ons fee duce SQ Sopp Dee euo vegeta sap de egeo 57 Ic 57 Solve Options dee aee ee eee V ee Re ei vex gov gt cesi epe ag eaae EN DERE teas ca iade eT Eve d eratac aee aaE 59 Setup Solver Pararneters teet e eene te uev rara er eue ee Gu evene xa rwera ge epe eor eeu uova ee ex ao gdE 59 Set p Analysis TYPE suceso etes dust cer vue eda ea E e mide a eas B DRE EN RU RR ERI Era 59 a ANSYS ICEM CFD 12 1 2009 SAS IP Inc All rights reserved Contains proprietary and confidential IV information of ANSYS Inc and its subsidiaries and affiliates User Manual Setup S D Case iora aiit eter rere EE P dn Ts eren eid 59 Write View Input file e 59 Submit Solver RUM 3 erectae eer ae ege aene opere pee ene OE tiae eeu ve a eee ue O Mey i eua Eu eee den 59 Post Process Results en dere beh eet hien t ea Sats i eee choca vad ee ie E Lad e eda eo toned dde ee dates 59 FEA Solver SUpport 255 iie erret eet et ene teresa eee aee ee nah ieee nee eee erba nne er ena dese esate en RUE END 59 Cart3D s
59. ou to minimize the number of output files generated with the multi block structured approach Blocking Strategy With Hexa the basic steps necessary to generate a hexahedral model are the same regardless of model complexity The blocking topology once initialized can then be modified by splitting and merging the blocks as well as through the use of an operation called O grid Refer to the next section While these op erations are performed directly on the blocks the blocks may also go through indirect modification by altering the sub entities of the blocks i e the vertices edges faces ANSYS ICEM CFD 12 1 2009 SAS IP Inc All rights reserved Contains proprietary and confidential information of ANSYS Inc and its subsidiaries and affiliates 39 Hexa Upon initialization Hexa creates one block that encompasses the entire geometry The subsequent operations under the Blocking menu of developing the block model referred to as blocking the geometry may be performed on a single block or across several blocks Note Note The topologic entities in Hexa are color coded based on their properties Colors of Edges White Edges and Vertices These edges are between two material volumes The edge and the associated vertices will be projected to the closest CAD surface between these material volumes The vertices of these edges can only move on the surfaces Blue Edges and Vertices These edges are in the volume The v
60. presents the number of elements Other functions which utilize this space will become pop up menus if the quality or histogram is enabled The Data Entry Zone DEZ The DEZ provides access to the parameters associated with a particular operation The controls utilized by the DEZ are described here Button Compute params A button is used to perform a function indicated by the button label Check Box M Smooth mesh A check box is used to enable disable an item or action indicated by the check box label Radio Buttons Method Update All C Keep Distributions C Keep Counts Curve gt Edge bunching Radio buttons are a set of check boxes with the condition that only one can be enabled at a time When you click the left mouse button on a radio button it will be enabled while all others will be disabled Drop Down List Mesh type Quad Dominant lv All Quad A drop down list is a hidden single selection list that shows only the current selection Click the arrow button to display the list Text Entry Name CURVEOO Text entries allow you to enter text associated with the label for the field Number Entry Min quality o4 Iterations 5 Number entries allow you to enter numerical values for the parameter indicated by the label for the field Some number entry fields may have arrow buttons which allow you to increase or decrease the value in entry field Selections Points 500 150 500 Vs Selection fi
61. rations You can choose to smooth some element types while freezing others Tetrahedral Mesh Coarsener During the coarsening process you can exclude surface or material domains If the Maintain surface sizes option is enabled during coarsening the resulting mesh satisfies the specified mesh size criteria on the geometric entities ANSYS ICEM CFD 12 1 2009 SAS IP Inc All rights reserved Contains proprietary and confidential 28 information of ANSYS Inc and its subsidiaries and affiliates Smooth Mesh Globally Triangular Surface Mesh Smoother The triangular surface mesh inherent in the Tetra mesh generation process can also be used independently of the volume mesh The triangular smoother marks all elements that are initially below the quality criterion and then runs the specified number of smoothing steps on the elements Nodes are moved on the actual CAD surfaces to improve the quality of the elements Triangular Surface Mesh Coarsener In the interest of minimizing grid points the coarsener reduces the number of triangles in a mesh by merging triangles This operation is based on the maximum deviation of the resultant triangle center from the surface the aspect ratio of the merged triangle and the maximum size of the merged triangle Triangular Surface Editing Tools There are tools available under the Edit Mesh menu for interactive mesh editing where nodes can be moved on the underlying CAD surfaces merged or even de
62. resents a perfect hexahedral cube while a value of 0 is a totally inverted cube with a negative volume The mesh quality measured on the x axis of all elements will be in the range from 0 to1 If the determinant value of a element is 0 the cube has one or more degenerated edges In general determinant values above 0 3 are acceptable for most solvers The y axis measures the number of elements that are represented in the histogram This scale ranges from 0 to a value that is indicated by the Height The subdivision among the quality range is determined by the number of assigned Bars ANSYS ICEM CFD 12 1 2009 SAS IP Inc All rights reserved Contains proprietary and confidential 46 information of ANSYS Inc and its subsidiaries and affiliates Warpage Angle The Angle option checks the maximum internal angle deviation from 90 degrees for each elements Various solvers have different tolerance limits for the internal angle check If the elements are distorted and the in ternal angles are small the accuracy of the solution will decrease It is always wise to check with the solver provider to obtain limits for the internal angle threshold Volume The Volume check will compute the internal volume of the elements in the model The units of the volume will be displayed in the unit that was used to create the model Warpage The Warpage check will yield a histogram that indicates the level of element distortion Nodes that are in
63. roblems The descriptions of each of these checks can be found in the Edit Mesh Check Mesh section of the Help Manual Smooth Mesh Globally After eliminating errors possible problems from a tetra mesh you need to smooth the grid using Edit Mesh Smooth Mesh Globally to improve the quality Smoothing iterations This value is the number of times the smoothing process will be performed Models with a more com plicated geometry will require a greater number of iterations to obtain the desired quality which is specified for Up to quality ANSYS ICEM CFD 12 1 2009 SAS IP Inc All rights reserved Contains proprietary and confidential information of ANSYS Inc and its subsidiaries and affiliates 29 Tetra Meshing Up to quality The Min value represents the worst quality while the Max value represents the highest quality elements Usually the Min value is set to 0 0 and the Max value is set to 1 0 The Up to quality value gives the smoother a quality to aim for Ideally after smoothing the quality of the elements should be higher than or equal to this value If this does not happen you should employ other methods of improving the quality such as merging nodes and splitting edges For most models the elements should all have ratios of greater than 0 3 while a ratio of 0 15 for complicated models is usually sufficient Freeze If the Freeze option is selected for an element type the nodes of this element type will be fixed d
64. rocesses The Message Window displays the communication between the GUI and the geometry and meshing functions You can review the information to be informed of the status of operations Any re quested information such as measure distance surface area etc will be reported in the message window Also internal commands can also be typed and invoked within the message window The Save command will write all message window contents to a file This file will be written to wherever ANSYS ICEM CFD was launched The Log check box allows only user specified messages to be saved to a file Note The Log file is unique from the file created with the Save button This file will be written to the starting directory and it interactively updates as more messages are recorded Once the check box is disabled you can continue to add to the file by enabling Log and accepting the same file name which is the default It will then continue to append this file The Histogram Window Figure The Histogram Window 18 12 wa pooysspeepssieqpospsspcput 0 01 02 03 04 05 06 07 08 09 1 ANSYS ICEM CFD 12 1 2009 SAS IP Inc All rights reserved Contains proprietary and confidential information of ANSYS Inc and its subsidiaries and affiliates 9 Introduction to ANSYS ICEM CFD The Histogram Window shows a bar graph representing the mesh quality The X axis represents element quality usually normalized to between 0 and 1 and the Y axis re
65. size by more than a factor of 2 Figure Full Tetra Enclosing the Geometry ANSYS ICEM CFD 12 1 2009 SAS IP Inc All rights reserved Contains proprietary and confidential information of ANSYS Inc and its subsidiaries and affiliates 25 Tetra Meshing Figure Full Tetra Enclosing the Geometry in Wire Frame Mode Figure Cross Section of the Tetra After this is done Tetra makes the mesh conformal that is it guarantees that each pair of adjacent elements will share an entire face The mesh does not yet match the given geometry so the mesher next rounds the nodes of the mesh to the prescribed points prescribed curves or model surfaces Tetra then cuts away all of the mesh which cannot be reached by a user defined material point without intersection of a surface ANSYS ICEM CFD 12 1 2009 SAS IP Inc All rights reserved Contains proprietary and confidential 26 information of ANSYS Inc and its subsidiaries and affiliates The Octree Mesh Method Figure Mesh after it captures surfaces and separation of useful volume ZINZIN ZINN ray Nai A K jaN a ROUA NANAY BADR 7 Noe KO ZEN ESE PSN BAA Se Figure Final Mesh before smoothing Finally the mesh is smoothed by moving nodes merging nodes swapping edges and in some cases deleting bad elements ANSYS ICEM CFD 12 1 2009 SAS IP Inc All rights reserved Contains proprietary and confidential information of ANSYS Inc and
66. t Curves and Points p 24 shows the resultant surface mesh if the curves and points are deleted from the geometry The hard features of the geometry are not preserved but rather are neglected or chamfered The boundary mesh nodes lie on the surfaces but they will only lie on the edges of the surfaces if curves and points are present Removal of curves and points can be used as a geometry defeaturing tool ANSYS ICEM CFD 12 1 2009 SAS IP Inc All rights reserved Contains proprietary and confidential 2 information of ANSYS Inc and its subsidiaries and affiliates 3 Tetra Meshing Figure Mesh Without Curves and Points Sizes on Surfaces and Curves To produce the optimal mesh it is essential that all surfaces and curves have the proper tetra sizes assigned to them For a visual representation of the mesh size select Geometry Surfaces Tetra Sizes from the Display Tree The same can be done with Curves Tetra icons will appear representing the element size of the mesh to be created on these entities Using the mouse you may rotate the model and visually confirm that the tetra sizes are appropriate If a curve or surface does not have an icon plotted on it the icon may be too large or too small to see In this case modify the mesh parameters so that the icons are visible in a normal display To modify the mesh size for all entities adjust the Scale Factor which is found under Mesh Global Mesh Setup Note that if th
67. t any format whether from a commercial CAD design package 3rd party universal database scan data or point data Beginning with a robust geometry module which supports the creation and modification of surfaces curves and points ANSYS ICEM CFD s open geometry database offers the flexibility to combine geometric information in various formats for mesh generation The resulting structured or unstructured meshes topology inter domain connectivity and boundary conditions are then stored in a database where they can easily be translated to input files formatted for a particular solver Overall Process The ANSYS ICEM CFD GUI Overall Process The generic working process involves the following 1 Open Create a project Create Manipulate the geometry Create the mesh Check Edit the mesh Generate the input for the solver oO m Bw NM Postprocess the results ANSYS ICEM CFD 12 1 2009 SAS IP Inc All rights reserved Contains proprietary and confidential information of ANSYS Inc and its subsidiaries and affiliates 1 Introduction to ANSYS ICEM CFD Figure The Overall Process Open Create Project Create Import Geometry Geometry Manipulation Clean up Create Mesh Set Parts zs Blocking Auto Sizing Default Method Type Set Mesh Sizes Quad Hexa Methods and Types m View Edit Pre Mesh Shell Mesh Auto Volume Mesh View Edit Mesh Solver Setup Output to Solver Run Solver Postprocess Opening Creating a Project
68. the Periodic Relationship nennen nennen nnne nennt nenne enne 46 Pre Mesh Quality os creed ror ap Raa heu o ri acf vomer nase Resa a Wai ar iiae lade Made OP Re dad 46 Determining the Location of Elements Js desi ee e Fey So eise ag uq ea e AER eunt d ERR HE Ag xe 46 IBI CERI Malin tics secs cR 46 Ande 2 aicacos cacy ese ra im Ran crar vti WA ed rgo Ra ne dr M oops ANNA VERTU aU pene de EST RR ERR 47 VOLUI steckt dun seus Dese rand Ouest vets esent ers c srt rela s NEP eda ME 47 Wal PaQe scsi cos 47 Properties neno EE 49 Create Material Property e mace isir Anaa e AEE E IEE E ENEE alti E OERE e 49 Save Material eresse e aiaa aa e a araa aaa de Na den aai a s aeaa ia aa d i Y ded dus 49 Open Material 5 tete ert eo aste exe Gas ade dere eee EATS EA eee unn Eleg aa ee el aa vu ETEK aaa ries 49 Define Table o pw REDIERE EUU E MAR T SEMEN SI a unas ane piae RM b Ur AU E etna 49 Define El ments oe ne eec eU Pre ree RU o a EI 49 CohlstEaInts solis Meca oa pec dina ds sube iata usd la SE a ta LP a Ru ere te ei cae 51 Create Constraint Displacement ccccccccesssessnsnccceeeecesseensnseeeceeeeseseesnnaeeeeeeeceseeeesaaeeeeeseseseeeennaeess 51 Define GOMLACE uet rt ip eas RU RAE Brad venga ta Eee Ubi i Kite t i RR Ra a Ee ARE Ea NIRE s 51 Define Single Surface COMMA sisne pred Rit deny eto aser degli a dedito quse seam vu sina euius 51 Define Initial Velocity eet cared Nae
69. tion of ANSYS Inc and its subsidiaries and affiliates 63 64 ANSYS ICEM CFD 12 1 2009 SAS IP Inc All rights reserved Contains proprietary and confidential information of ANSYS Inc and its subsidiaries and affiliates
70. tly allows for better resolution more calculations per unit distance of the solution normal to the surface without increasing the number of elements along the surface This gives you a quicker and more accurate solution than a very fine tetra mesh The height and direction of the prism layer extrusion are calculated on an element by element basis and may vary due to global or local controls or for improved quality You may want to set the initial height number of layers and growth ratio and then they limit this with the Prism height limit factor Or you may prefer to just set the number of layers and growth ratio This allows Prism to adjust the initial height and locally optimize the volume transition between the prisms and tetras Users concerned about Y can then adjust the first cell height using Edit Mesh Split Mesh Split Prisms Prism parameters are set globally but can then be adjusted on a part by part or entity by entity basis Entity settings override global settings and between entities the smaller size overrides the larger For instance 3 layers could be set for a growth rate of 1 2 globally but a certain part could be set for 5 layers On a specific entity within that part or another part you could set a specific parameter If you set prism parameters such as height on a curve entities it will interpolate that parameter across the surface between the curves You may notice that you can also select volume parts for prism
71. tric changes in geometry Symmetry As necessary in analyzing rotating machinery applications for example Hexa allows you to take advantage of symmetry in meshing a section of the rotating machinery thereby minimizing the model size Link Shape This allows you to link the edge shape to existing deforming edge This gives better control over the grid specifically in the case of parametric studies Adjustability Options to generate 3 D surface meshes from the 3 D volume mesh and 2 D to 3 D block topology transformation Mesh Generation with Hexa To generate a mesh within Hexa you need to Import a geometry file using any of the direct indirect or faceted data interfaces interactively define the block model through split merge O grid definition edge face modifications and vertex movements Check the block quality to ensure that the block model meets specified quality thresholds Assign edge meshing parameters such as maximum element size initial element height at the bound aries and expansion ratios Generate the mesh with or without projection parameters specified CheckMesh quality to ensure that specified mesh quality criteria are met Write Output files to the desired solvers If necessary you may always return to previous steps to manipulate the blocking if the mesh quality does not meet the specified threshold or if the mesh does not capture certain geometry features The blocking may be saved at any tim
72. ts The various GUI components are described in the following sections Main Menu Utilities Function Tabs The Display Control Tree The Message Window The Histogram Window The Data Entry Zone DEZ Main Menu Figure The Main Menu NA BD Edea The Main Menu provides access to the following pull down menus ANSYS ICEM CFD 12 1 2009 SAS IP Inc All rights reserved Contains proprietary and confidential 6 information of ANSYS Inc and its subsidiaries and affiliates GUI Components File Menu contains options for creating new or opening existing projects loading and saving files importing and exporting geometry and initializing scripting Edit Menu contains Undo Redo options the option to open a shell window and various internal mesh geometry conversion commands View Menu contains various options for the standard views view controls and annotations Info Menu allows you to get various information regarding geometry mesh and individual entities Settings Menu contains default settings for performance graphics and other settings most likely to be used more than 9096 of the time by a specific user Help Menu contains links to Help Topics tutorials the User s Guide and version information Utilities Figure Utilities Cay a CRUCES o x El D fa E11 Re The Utilities are icon representations of some of the most commonly used functions in the Main Menu in cluding opening closing a project u
73. ty This allows you to define initial nodal point translational velocities by specifying the directional and rotational velocity for nodal sets Define Planar Rigid wall You can define a Planar Rigid Wall by specifying the Head and Tail coordinates ANSYS ICEM CFD 12 1 2009 SAS IP Inc All rights reserved Contains proprietary and confidential 1 information of ANSYS Inc and its subsidiaries and affiliates 5 52 ANSYS ICEM CFD 12 1 2009 SAS IP Inc All rights reserved Contains proprietary and confidential information of ANSYS Inc and its subsidiaries and affiliates Loads In this tab there are several options available for applying internal and external loads such as force pressure and temperature Theory Force Distribution follows the following formulation Curve Total Force FT is applied on the curve as shown below where L1 is the length of Element 1 0 and 1 are the node number connecting Element 1 Figure Elements on Curve Li L2 L3 LA Then the force distribution on Linear elements as per the FEA concept is shown in the figure below ANSYS ICEM CFD 12 1 2009 SAS IP Inc All rights reserved Contains proprietary and confidential information of ANSYS Inc and its subsidiaries and affiliates 53 Loads Figure Force Distribution as per the FEA concept 0 5 FT L1 LT 0 5 FT L1 LT e L1 e 0 1 0 5 FT L2 LT 0 5 FT L2 LT i i 1 L2 2 O 5 FT L3ILT 0 5 F
74. uality Mets sies eher Dea OE E REA M PR UR He RR ced E ER Kup vi ees Fue seu Fa pun s M i 31 Advanced Options for Smoothing Mesh out vase eor tee sped spin CEU podes equ oa pieta ed 31 Prism Mesh erii saad van REQUIRE Maid atacado ela a dades aca dada la del Aer di e udi t dre ates 33 Prism Mesh PIOCOBE sides dp da Rp on ox Rad np RN GERE MAUS dO ARR RN CON sve adag ut ic aeS kAS 34 Prism Mesh Preparatiori 2 metere tinte need aede Ege eee nere aeuo Te ERU NSe ve Ln ge ee eo 34 Smoothing Tetra Prisim2oMeshi se rape eorr Re pali aaa PI Aw b Qu Seu eb Devi era oet E PDT ERA ET RUE 35 POM m TE 37 ANSYS ICEM CFD 12 1 2009 SAS IP Inc All rights reserved Contains proprietary and confidential S information of ANSYS Inc and its subsidiaries and affiliates n User Manual Introd toTc ocior ops Duden abb nod ebd E a E vg bu a EE et Rd epi edg 37 Featuresof Hexa sinus ccisdtea LITT E IU 37 Mesh Generation with Hexa neriasi eere sadeacy avtvcatsencckedeaveccawassdevekssveuavearndedersadestuaeadeece avevens 38 Mida c Datta a PN ery nnaou aea ie a eaaa aaa ana as Sedea Eaa aae aa Eikai acumen 38 Intelligent Geometry in HeXai ieies irei apaiia Ae oboe tue UR ae i ned apte e rte 39 Unstructured and Multi block Structured Meshes 0 0 0 eseeeeessseeeeeesseeeceessaeeeeeessaeeecessaneeceessaeeesessaaeeeeeses 39 Unstructured Mesh O tpUt 5 Ier etie eo pe e REDDE Ee eO PAGES EUR ua SEDE Eee Yen 39 Multi Block Structured Mesh Output
75. uring the smoothing operation As a result this element type will not be displayed in the histogram Float If the Float option is selected the nodes of the specified element type will capable of moving freely allowing nodes that are common with another type of element to be smoothed The quality of elements set to float is not tracked during the smoothing process and so the quality is not displayed in the histo gram The tetrahedral quality will be displayed within the Quality Histogram where 0 represents the worst aspect ratio and 1 represents the best aspect ratio You may modify the display of the histogram by adjusting the values of Min Max Height and Bars These options as well as the following options can be accessed by right clicking on the histogram The Replot option allows you to change the following parameters in the window that will appear Clicking Accept will replot the histogram to the newly set values Min X Value This minimum value which is located on the left most side of the histogram s x axis represents the worst quality elements Max X Value This maximum value which is located on the right most side of the histogram s x axis represents the highest quality that elements can achieve Max Y height You can adjust the number of elements that will be represented on the histogram s y axis Usually a value of 20 is sufficient If there are too many elements displayed it is difficult to discern the effects of smoot

Documentation for ANSYS ICEM CFD 12.1

Contents

Download Pdf Manuals

Related Search

Related Contents