Hướng dẫn phương pháp meshing bằng ansys full

ANSYS Meshing User's Guide ANSYS, Inc Southpointe 275 Technology Drive Canonsburg, PA 15317 ansysinfo@ansys.com http://www.ansys.com (T) 724-746-3304 (F) 724-514-9494 Release 13.0 November 2010 ANSYS, Inc is certified to ISO 9001:2008 Copyright and Trademark Information © 2010 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 documentation are furnished by ANSYS, Inc., its subsidiaries, or affiliates under a software license agreement that contains provisions 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 documentation 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, duplication, 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 Capabilities in Workbench Meshing Overview Meshing Implementation in ANSYS Workbench Types of Meshing Meshing by Algorithm Meshing by Element Shape Conformal Meshing Between Parts Usage in Workbench 11 Basic Meshing Application Workflows 11 Overview of the Meshing Process in ANSYS Workbench 11 Overview of the Meshing Process for CFD/Fluids Analyses 12 Combining CFD/Fluids Meshing and Structural Meshing 13 Strategies for CFD/Fluids Meshing in ANSYS Workbench 15 Accessing Meshing Functionality 17 Overview of the Meshing Application Interface 18 Determination of Physics, Analysis, and Solver Settings 19 Working with Legacy Mesh Data 20 Exporting Meshes or Faceted Geometry 22 Mesh Application File Export 23 FLUENT Mesh Export 23 Classes of Zone Types in ANSYS FLUENT 25 Standard Naming Conventions for Naming Named Selections 27 Zone Type Assignment 28 Example of ANSYS FLUENT Workflow in ANSYS Workbench 32 POLYFLOW Export 35 CGNS Export 36 ICEM CFD Export 36 Exporting Faceted Geometry to TGrid 44 Extended ANSYS ICEM CFD Meshing 47 Writing ANSYS ICEM CFD Files 47 Rules for Interactive Editing 49 Limitations of ANSYS ICEM CFD Interactive 49 Working with Meshing Application Parameters 49 ANSYS Workbench and Mechanical APDL Application Meshing Differences 50 Mesh Controls Overview 53 Global and Local Mesh Controls 53 Understanding the Influence of the Advanced Size Function 53 Global Mesh Controls 57 Defaults Group 57 Physics Preference 57 Solver Preference 59 Relevance 59 Sizing Group 59 Use Advanced Size Function 59 Curvature Size Function 61 Proximity Size Function 61 Fixed Size Function 62 Specifying Size Function Options 62 Curvature Normal Angle 63 Proximity Accuracy 63 Release 13.0 - © SAS IP, Inc All rights reserved - Contains proprietary and confidential information of ANSYS, Inc and its subsidiaries and affiliates iii ANSYS Meshing User's Guide Num Cells Across Gap 63 Proximity Size Function Sources 64 Min Size 64 Max Face Size 64 Max Size 65 Growth Rate 65 Relevance Center 65 Element Size 66 Initial Size Seed 66 Smoothing 66 Transition 67 Span Angle Center 67 Minimum Edge Length 67 Inflation Group 67 Use Automatic Inflation 69 None 69 Program Controlled 69 All Faces in Chosen Named Selection 70 Inflation Option 71 Transition Ratio 72 Maximum Layers 73 Growth Rate 73 Number of Layers 73 Maximum Thickness 73 First Layer Height 74 First Aspect Ratio 74 Aspect Ratio (Base/Height) 74 Inflation Algorithm 74 View Advanced Options 77 Collision Avoidance 77 Fix First Layer 81 Gap Factor 81 Maximum Height over Base 81 Growth Rate Type 82 Maximum Angle 82 Fillet Ratio 83 Use Post Smoothing 84 Smoothing Iterations 84 CutCellMeshing Group 84 Active 84 Feature Capture 84 Tessellation Refinement 85 Advanced Group 85 Shape Checking 85 Element Midside Nodes 87 Straight Sided Elements 88 Number of Retries 88 Extra Retries For Assembly 89 Rigid Body Behavior 89 Mesh Morphing 89 Defeaturing Group 90 Pinch 90 iv Release 13.0 - © SAS IP, Inc All rights reserved - Contains proprietary and confidential information of ANSYS, Inc and its subsidiaries and affiliates ANSYS Meshing User's Guide Pinch Control Automation Overview 93 How to Define Pinch Control Automation 96 How to Define or Change Pinch Controls Manually 97 Usage Information for Pinch Controls 97 Loop Removal 99 Automatic Mesh Based Defeaturing 99 Statistics Group 101 Nodes 101 Elements 101 Mesh Metric 101 Element Quality 106 Aspect Ratio Calculation for Triangles 106 Aspect Ratio Calculation for Quadrilaterals 107 Jacobian Ratio 108 Warping Factor 110 Parallel Deviation 113 Maximum Corner Angle 114 Skewness 114 Orthogonal Quality 117 Local Mesh Controls 121 Method Control 122 Method Controls and Element Midside Nodes Settings 122 Setting the Method Control for Solid Bodies 125 Automatic Method Control 125 Tetrahedrons Method Control 125 Patch Conforming Algorithm for Tetrahedrons Method Control 125 Patch Independent Algorithm for Tetrahedrons Method Control 126 Hex Dominant Method Control 146 Sweep Method Control 147 MultiZone Method Control 150 Setting the Method Control for Surface Bodies 155 Quadrilateral Dominant Method Control 155 Triangles Method Control 155 Uniform Quad/Tri Method Control 156 Uniform Quad Method Control 157 Sizing Control 157 Using the Local Sizing Control 158 Defining Local Mesh Sizing on a Body 158 Defining Local Mesh Sizing on a Face 159 Defining Local Mesh Sizing on an Edge 159 Defining Local Mesh Sizing on a Vertex 159 Descriptions of Local Sizing Control Options 160 Notes on Element Sizing 164 Contact Sizing Control 166 Refinement Control 167 Mapped Face Meshing Control 168 Setting Basic Mapped Face Meshing Controls 168 Understanding Advanced Mapped Face Meshing Controls 169 Restrictions Related to Vertex Types 170 Restrictions Related to Edge Mesh Intervals 171 Selecting Faces and Vertices 171 Effect of Vertex Type on Face Meshes 173 Release 13.0 - © SAS IP, Inc All rights reserved - Contains proprietary and confidential information of ANSYS, Inc and its subsidiaries and affiliates v ANSYS Meshing User's Guide Setting Advanced Mapped Face Meshing Controls 174 Notes on the Mapped Face Meshing Control 175 Match Control 177 Cyclic Match Control 178 Arbitrary Match Control 179 Pinch Control 181 Defining Pinch Controls Locally 181 Changing Pinch Controls Locally 183 Inflation Control 185 Gap Tool 188 Options 191 Accessing the Options Dialog Box 191 Common Settings Option on the Options Dialog Box 191 Meshing Options on the Options Dialog Box 192 Specialized Meshing 195 Mesh Sweeping 195 Thin Model Sweeping 199 MultiZone Meshing 212 MultiZone Overview 213 MultiZone Support for Inflation 213 MultiZone Support for Defined Edge and Face Sizings 214 MultiZone Algorithms 214 Using MultiZone 216 MultiZone Source Face Selection Tips 219 MultiZone Source Face Imprinting Guidelines 219 Internal Loops 220 Boundary Loops 220 Multiple Internal Loops 221 Multiple Connected Internal Loops 222 Internal Cutout Loops 223 Parallel Loops 225 Intersecting Loops 226 Using Virtual Topology to Handle Fillets in MultiZone Problems 227 MultiZone Limitations and Hints 227 CutCell Meshing 228 The CutCell Meshing Process 228 The CutCell Meshing Workflow 231 Direct Meshing 239 Inflation Controls 244 Mesh Refinement 250 Mixed Order Meshing 250 Air Gap Meshing 250 Contact Meshing 251 Winding Body Meshing 251 Wire Body Meshing 251 Pyramid Transitions 251 Match Meshing and the Symmetry Folder 251 Rigid Body Meshing 251 Thin Solid Meshing 254 CAD Instance Meshing 254 Meshing and Hard Entities 256 Baffle Meshing 257 vi Release 13.0 - © SAS IP, Inc All rights reserved - Contains proprietary and confidential information of ANSYS, Inc and its subsidiaries and affiliates ANSYS Meshing User's Guide Mesh Control Interaction Tables 261 Interactions Between Mesh Methods 261 Interactions Between Mesh Methods and Mesh Controls 263 Miscellaneous Tools 267 Generation of Contact Elements 267 Renaming Mesh Control Tool 267 Mesh Numbering 268 Mesh Connection 268 Ease of Use Features 269 Updating the Mesh Cell State 269 Generating Mesh 270 Previewing Surface Mesh 271 Exporting a Previewed Surface Mesh in FLUENT Format 273 Previewing Source and Target Mesh 273 Previewing Inflation 274 Exporting a Previewed Inflation Mesh in FLUENT Format 275 Showing Program Controlled Inflation Surfaces 275 Showing Sweepable Bodies 276 Showing Problematic Geometry 276 Showing Geometry in Overlapping Named Selections 276 Showing Removable Loops 277 Inspecting Large Meshes Using Named Selections 277 Clearing Generated Data 277 Showing Missing Tessellations 278 Showing Mappable Faces 279 Virtual Topology 281 Introduction 281 Creating Virtual Cells 281 Creating Virtual Split Edges 285 Named Selections and Regions for CFX 291 Troubleshooting 293 Tutorials 299 Tutorial 1: Can Combustor 299 Geometry Import 300 Mesh Generation 302 Tutorial 2: Single Body Inflation 307 Tutorial Setup 308 Mesh Generation 308 Tutorial 3: Mesh Controls and Methods 318 Tutorial Setup 318 Mesh Generation 319 Index 337 Release 13.0 - © SAS IP, Inc All rights reserved - Contains proprietary and confidential information of ANSYS, Inc and its subsidiaries and affiliates vii viii Release 13.0 - © SAS IP, Inc All rights reserved - Contains proprietary and confidential information of ANSYS, Inc and its subsidiaries and affiliates Capabilities in Workbench The following topics are discussed in this section Meshing Overview Meshing Implementation in ANSYS Workbench Types of Meshing Conformal Meshing Between Parts Meshing Overview Philosophy The goal of meshing in ANSYS Workbench is to provide robust, easy to use meshing tools that will simplify the mesh generation process These tools have the benefit of being highly automated along with having a moderate to high degree of user control Physics Based Meshing When the Meshing application is launched (that is, edited) from the ANSYS Workbench Project Schematic, the physics preference will be set based on the type of system being edited For analysis systems, the appropriate physics is used For a Mechanical Model system, the Mechanical physics preference is used For a Mesh system, the physics preference defined in Tools> Options> Meshing> Default Physics Preference is used Upon startup of the Meshing application from a Mesh system, you will see the Meshing Options panel shown below This panel allows you to quickly and easily set your meshing preferences based on the physics you are preparing to solve If you remove the panel after startup, you can display the panel again by clicking the Options button from the Mesh toolbar Release 13.0 - © SAS IP, Inc All rights reserved - Contains proprietary and confidential information of ANSYS, Inc and its subsidiaries and affiliates Capabilities in Workbench Physics Preference The first option the panel allows you to set is your Physics Preference This corresponds to the Physics Preference value in the Details View of the Mesh folder Setting the meshing defaults to a specified “physics” preference sets options in the Mesh folder such as Relevance Center, midside node behavior, shape checking, and other meshing behaviors Note The Physics Preference is selectable from the Meshing Options panel only if the Meshing application is launched from a Mesh component system or a Mechanical Model component system If the Meshing application is launched from an analysis system (whether it be via the Model cell in a non-Fluid Flow analysis system or the Mesh cell in a Fluid Flow analysis system), you must use the Details View of the Mesh folder to change the Physics Preference See Determination of Physics, Analysis, and Solver Settings (p 19) for more information Mesh Method Setting the Physics Preference option also sets the preferred Mesh Method option for the specified physics All of the meshing methods can be used for any physics type, however we have found that some of our meshers are more suitable for certain physics types than others The preferred ANSYS Workbench Mesh Methods are listed below grouped by physics preference Release 13.0 - © SAS IP, Inc All rights reserved - Contains proprietary and confidential information of ANSYS, Inc and its subsidiaries and affiliates Tutorial 14: CAD Cleanup and Meshing You will now merge the narrow face with its neighbor to eliminate it completely In the Tree View, right-click on Virtual Topology and select Insert > Virtual Face For Location, hold down the Ctrl key and click to pick the two faces highlighted in the picture below Click Apply in the Details View to confirm the selection Now, re-generate the surface mesh to see the effect of this Right-click over Default Preview Group in the Tree View, and select Generate Surface Meshes 234 Release 12.1 - © 2009 SAS IP, Inc All rights reserved - Contains proprietary and confidential information of ANSYS, Inc and its subsidiaries and affiliates Adding Virtual Faces and Virtual Edges The narrow face has now disappeared from the mesh and most of the small and distorted triangles that it caused have also gone However, there is still a short edge which used to form the edge of the narrow face, and as a result there are still two poor triangles with very small angles You may need to zoom in to see these triangles Now create a Virtual Edge to remove this edge and the poor triangles In the Tree View, right-click on Virtual Topology and select Insert > Virtual Edge For Location, Ctrl-click to pick the two edges highlighted in the picture below Click Apply in the Details View to confirm the selection Now re-generate the surface mesh to see the effect of this Right-click over Default Preview Group in the Tree View, and select Generate Surface Meshes The distorted triangles have completely disappeared as the mesher no longer needs to resolve the short edge You will need to zoom out to see the triangles properly as they are so much larger than before Now that you have seen the effect of short edges and how to remove them manually, you will now see how to remove them automatically First turn on automatic edge merging again Release 12.1 - © 2009 SAS IP, Inc All rights reserved - Contains proprietary and confidential information of ANSYS, Inc and its subsidiaries and affiliates 235 Tutorial 14: CAD Cleanup and Meshing From the menu bar, select Tools > Options Expand the options tree and select Meshing > Meshing Under the sub-section Virtual Topology, set Merge Edges Bounding New Virtual Faces to Yes Click on OK to apply the change You will need to delete both the Virtual Edge and the Virtual Face to see the effect of this setting because it applies only when new Virtual Faces are created Right-click over Virtual Edge in the Tree View and select Delete Right-click over Virtual Face in the Tree View and select Delete If you want, you can verify at this point that the surface mesh is poor again by regenerating it Now re-create the Virtual Face you made previously In the Tree View, right-click on Virtual Topology and select Insert > Virtual Face For Location, pick the two faces highlighted in the picture below Press Apply in the Details View to confirm the selection If you now inspect the Tree View, you should be able to see a new entry immediately below Virtual Face 1, that is, Virtual Edge If you click on it to highlight it in the Graphics window, you can see that it corresponds to the same Virtual Edge as you previously created manually Now that automatic edge merging is turned on, CFX-Mesh behaves intelligently and creates all the related Virtual Edges that it can each time it creates a Virtual Face Note that CFX-Mesh will not automatically merge edges that meet at an angle greater than a certain tolerance (the default is degrees) so that corners will be preserved This tolerance can be changed using Tools > Options and setting Meshing > CFX-Mesh Options > Virtual Topology > Automatic Edge Merging Tolerance (Degrees) You can now create several more Virtual Faces to remove the remaining narrow faces and corresponding short edges In the Tree View, right-click on Virtual Topology and select Insert > Virtual Face For Location, start by picking the four narrow faces highlighted in the picture below (do not press Apply yet) These faces are most easily selected by using Box Select (drag a box with the left mouse button over each face in turn, holding down the Ctrl key for the second and subsequent faces) 236 Release 12.1 - © 2009 SAS IP, Inc All rights reserved - Contains proprietary and confidential information of ANSYS, Inc and its subsidiaries and affiliates Adding Virtual Faces and Virtual Edges Now add a further fourteen faces to the selection, shown in the picture below Press Apply in the Details View to confirm the selection In the Tree View, right-click on Virtual Topology and select Insert > Virtual Face For Location, pick the narrow face highlighted in the picture below, using Box Select Then add three more faces as shown in the next picture: Press Apply in the Details View to confirm the selection Note that various Virtual Edges have been automatically created Release 12.1 - © 2009 SAS IP, Inc All rights reserved - Contains proprietary and confidential information of ANSYS, Inc and its subsidiaries and affiliates 237 Tutorial 14: CAD Cleanup and Meshing So far, all of the Virtual Faces you have created have merged faces that meet at a tangent; that is, the resulting Virtual Face is smooth and contains no sharp corners In this situation, there is no loss of accuracy resulting from the creation of the Virtual Face However, it is possible to create Virtual Faces that contain sharp corners: in the Virtual Face created below, two of the faces meet at right angles Where this occurs, the mesher effectively rounds off the corner and so the meshed geometry is only an approximation to the original geometry You should merge faces into a non-smooth Virtual Face only where there is a small feature present in the geometry that does not need to be included in the CFD simulation In the Tree View, right-click on Virtual Topology and select Insert > Virtual Face For Location, pick the narrow face highlighted in the picture below, using Box Select Then add a second face as shown in the next picture: Press Apply in the Details View to confirm the selection Right-click over Default Preview Group again and select Generate Surface Meshes Zoom into the region of the mesh highlighted below Notice how the mesh in the region of the narrow face is not flat; the corner has been rounded off There are still two short edges where the ends of the narrow face used to be, which results in large numbers of small mesh elements as the mesher resolves the short edges These short edges could not be automatically merged with another edge to form a Virtual Edge The edge at the bottom (in the area highlighted in the picture above) makes an angle of greater than degrees with its neighbor so the corresponding Virtual 238 Release 12.1 - © 2009 SAS IP, Inc All rights reserved - Contains proprietary and confidential information of ANSYS, Inc and its subsidiaries and affiliates Removing the Remaining Short Edges Edge could have been created if this tolerance had been increased However, the edge at the top cannot be created as a Virtual Edge for reasons discussed in the next section Apart from these two small patches of fine and distorted mesh, the surface mesh is now much more uniform and of a much higher quality due to the creation of the Virtual Faces and Edges Removing the Remaining Short Edges The two remaining patches of fine mesh are due to the two remaining short edge However, it is the top patch of fine mesh (highest y-value) that causes the problem Its topology is shown in the picture below: edges are shown in blue and vertices in red You need to remove this short edge to eliminate the fine mesh that it forces the mesher to create However, you cannot so by creating another Virtual Edge A Virtual Edge can be created only from edges that share the same faces, and there is no other edge that shares the same faces as this remaining short edge, as the diagram above shows Note It would have been easy to choose a different set of faces to be used in the construction of the last Virtual Face that would have avoided this problem; this tutorial has deliberately set up this problem edge in order to illustrate how it can be removed Making a different Virtual Face may not always be possible in complex CAD where features may need to be preserved CFX-Mesh allows you to remove short edges using a second method: Short Edge Removal Using this mechanism, short edges are removed by collapsing them to a single point As a result (and unlike Virtual Edges), this method cannot be used if the local mesh length scale is smaller than the length of the edges to be removed, as it leads to the mesh becoming distorted (see the CFX-Mesh Help for more details) You need to determine how long this edge is and compare it to the mesh length scale before using Short Edge Removal to remove it Also, when using Short Edge Removal, you simply specify a length scale, and all edges in the geometry which are shorter than this length scale are removed It is therefore a good idea to make sure that before you use it, you know exactly which edges will be removed Both of these things can be checked by using CAD Check again Click on the plus sign next to Geometry in the Tree View to open it up Click on Verify Options In the Details View, you can set the parameters to be used by CAD Check to identify poor geometry In this case, you are interested only in short edges Set Short Edge Limit to 0.015 m to make CAD Check identify all of the edges shorter than this length Right-click over Geometry and select Verify Geometry to perform the CAD Check operation Once the CAD Check operation has finished, check the error messages in the Messages window Release 12.1 - © 2009 SAS IP, Inc All rights reserved - Contains proprietary and confidential information of ANSYS, Inc and its subsidiaries and affiliates 239 Tutorial 14: CAD Cleanup and Meshing Note that the total number of warnings has decreased from when you ran CAD Check on the original geometry (before creating Virtual Edges and Virtual Faces) There are no longer any warnings about CAD faces with small angles or potential sliver faces, since all of these faces have been removed by the creation of Virtual Faces There is just one warning about short edges (plus the second warning which gives a summary of the checks) Click on the warning message about the short edges, and verify that the highlighted edges correspond to only the two edges which you have already identified as needing removal This means that you can ask to remove all edges of less than 0.015 m from the geometry, knowing that it only affects the required edges Since you are going to use a mesh length scale which is significantly larger than 0.015 m, the short edge can be safely removed using Short Edge Removal Under Geometry in the Tree View, click on Fix Options In the Details View, set Remove Short Edges to Yes, and set Short Edge Tolerance [m] to 0.015 m Now regenerate the surface mesh by right-clicking over Default Preview Group and select Generate Surface Meshes Once the meshing operation has finished, you should be able to see that the remaining patches of fine mesh have now disappeared Click on Mesh Statistics under Default Preview Group in the Tree View, and check the Details View to see the mesh statistics You should find that your surface mesh has around 2000-2500 triangles Removing the narrow faces and short edges has allowed you to create a good-quality mesh with far fewer triangles than previously Setting up the Finer Mesh Set a finer Maximum Spacing (note that this should always remain above the 0.015 m that was set as the limit for Short Edge Removal): Click on Default Body Spacing in the Tree View, which is contained in Mesh > Spacing In the Details View, change Maximum Spacing to 0.05 m, and press Enter on the keyboard to set this value Click on Default Face Spacing in the Tree View, which is contained in Mesh > Spacing In the Details View, change Angular Resolution to 18 degrees Setting up Inflation You will now add inflation onto the walls First create a Composite 2D Region to allow the appropriate faces to be selected more easily Create a Composite 2D Region called NoInflation on the faces highlighted in the picture below Click on Inflation in the Tree View In the Details View, set Number of Inflated Layers to Set Expansion Factor to 1.3 Leave the rest of the parameters as their default values 240 Release 12.1 - © 2009 SAS IP, Inc All rights reserved - Contains proprietary and confidential information of ANSYS, Inc and its subsidiaries and affiliates Generating the Volume Mesh In the Tree View, right-click on Inflation and select Insert > Inflated Boundary For Location, select Default 2D Region from the Tree View Set Maximum Thickness to 0.05 m Now regenerate the surface mesh to inspect the refined and inflated mesh Right-click over Default Preview Group and select Generate Surface Meshes Generating the Volume Mesh Finally, you can generate the volume mesh by right-clicking Mesh in the Tree View and selecting Generate Volume Mesh This completes the mesh generation Now save the project by selecting File > Save from CFX-Mesh's main menu and return to the Project Schematic You can exit from ANSYS Workbench by selecting File > Exit from the main menu Release 12.1 - © 2009 SAS IP, Inc All rights reserved - Contains proprietary and confidential information of ANSYS, Inc and its subsidiaries and affiliates 241 242 Release 12.1 - © 2009 SAS IP, Inc All rights reserved - Contains proprietary and confidential information of ANSYS, Inc and its subsidiaries and affiliates Index Symbols 2D generating an extruded 2D mesh, 87 selecting 2D regions and faces - See also regions, 57 3D using the advancing front and inflation for volume meshing, 87 A adding guidelines for creating and adding - virtual face and virtual edge - See also checking; meshing; virtual topology, 47 angular resolution specifying the curvature for an edge or face in terms of an angle, 67 aspect ratio effects due to 2D extrusion options, 91 effects due to inflation, 82 B box select specifying a location, 14 C CFX-Mesh GUI - See also examples; features; tutorials, meshing features, 63 tutorials , 122 checking error messages - See also geometry; meshing; troubleshooting, 41 faces with high sliver factor, 43 mesh quality, 80 parameterization face, 43 parameterization quality, 43 sliver edge - locating short edges in the geometry, 42 clearing removing the surface mesh from application's memory , 97 user-defined settings using the File menu command, Composite 2D regions description - See also regions, 58 computation of sliver factor, 43 coordinates double-precision - storing the mesh and region information , 101 for point selection, 13 mapping - between surface mesh and solid geometry , 37 creating Composite 2D regions and Default 2D regions , 58 mesh - an overview, D Default 2D region description - See also regions, 58 defining regions, degenerate geometry - See also geometry, 40 Details View, 21 Display Units dialog accessing in DesignModeler, 128 displaying - See also viewing, 22 E elements aspect ratio - controlling the size and distribution of elements , 75 aspect ratio and distribution for extruded mesh, 91 checking the mesh quality, 80 distortion of interstitial elements, 80 error messages checking the undesirable geometry - See also geometry; meshing; troubleshooting, 41 examples creating a free floating thin surface, 36 creating a virtual edge, 51 creating a virtual face, 48 creating an attached thin surface, 36 poorly-parameterized surfaces - circular parametric surface, 39 poorly-parameterized surfaces - cusps, 40 poorly-parameterized surfaces - degenerate surfaces, 40 poorly-parameterized surfaces - distorting the square, 39 poorly-parameterized surfaces - uneven parametric lines, 39 removing the short edges, 53 exporting mesh settings as a CCL file, F features 2D region groups, 122 Release 12.1 - © 2009 SAS IP, Inc All rights reserved - Contains proprietary and confidential information of ANSYS, Inc and its subsidiaries and affiliates 243 Index advancing front surface mesher, 87 advancing front volume mesher, 88 advancing front with inflation 3D, 88 CAD check, 122 checking the undesirable geometry, 41 curvature-sensitive meshing, 122 delaunay surface mesher, 87 description of mesh controls, 68 extruded 2D meshing, 90, 122 face spacing, 122 geometry update, 122 global mesh scaling, 86 inflation, 75, 122 list of meshing functions to control mesh generation, 63 listed - See also examples; tutorials, 122 meshing controls, 122 Named Selections, 59 parallel volume meshing, 88, 122 periodicity, 122 periodicity - generating the mesh for periodic boundary conditions, 72 preview groups, 122 proximity, 122 proximity - controlling the mesh refinement around edges and faces, 84 short edge removal, 122 spacing - specifying the mesh length scale, 63 specifying the meshing strategy, 87 stretch, 122 stretch - expanding or contracting the mesh element, 83 surface meshing, 87 virtual faces and edges, 122 file formats gtm, 101 mshdb, 101 first layer thickness inflation - specifying the height for the first prism layer, 77 fixing - See also geometry, 44 flood select specifying a location, 14 G generate surface mesh, 16 surface meshes, 97 volume mesh, 16 generating preview group - selecting 2D regions, 97 surface mesh, 244 volume mesh, 3, 101 geometry controlling the appearance, 46 creating 2D regions for thin surfaces , 37 degenerate entities, 40 for CFX-Mesh , meshing the special topologies - faces of an inflated boundary, 34 meshing the special topologies - faces of solid bodies, 32 meshing the special topologies - solid bodies, 27 modeling consideration for thin surfaces, 35 modeling guidelines to improve poorly-parameterized surfaces, 37 modifying and updating, 25 requirements for meshing , 26 sliver edge checking, 44 suppressing items in the Tree View, 19 Verify Geometry - setting the tolerances and limits for the geometry checking - See also checking, 43 verifying and updating the geometry using the toolbar , 15 graphics window, 22 GUI - See also toolbars; viewing, guidelines selection of 2D regions and faces, 57 specifying the mesh length scale, 115 to create virtual topology, 47 H help context sensitive, GUI - an overview , meshing features, 63 hiding objects, 20 highlight See also checking; tree view; viewing, 17 I inflation, 75 consideration for the faces with thin gaps , 82 consideration for the inside walls of cylindrical pipes, 82 controlling the advanced mesh quality, 80 creating an inflated boundary, 81 list of available parameters to control inflation, 76 interrupt description - See also toolbars, 16 Release 12.1 - © 2009 SAS IP, Inc All rights reserved - Contains proprietary and confidential information of ANSYS, Inc and its subsidiaries and affiliates Index L length unit setting in DesignModeler, 128 limits - See also tolerance, 43 line control description, 70 location selecting multiple items, 12 selection, 12 M menus - description of menu items, merging See also virtual topology, 48 mesh adaption - using ANSYS CFX-Pre , attributes - setting the length scale, generating volume mesh, 101 generator - 3D meshing mode , generator - extrude 2D meshing mode, guidelines for mesh length scale, 115 mesh edge length - viewing the element size range , 14 problems with degenerate geometry , 40 selecting and previewing mesh faces , 97 types of controls available for mesh refinement , 68 meshing advancing front surface mesher, 87 an overview of the meshing process, delaunay surface mesher, 87 extruded 2D, 90 extruded 2D meshing , 94 generator, halting the meshing process, 16 list of features, 63 mesh generation process for a periodic pair , 74 parallel volume meshing, 88 skipping the geometry creation - using tutorials,119 strategy - controlling the global meshing behavior , 87 toolbar, 16 tutorials - See also examples , 122 inflation - first layer thickness, 77 inflation - total thickness , 79 parallel volume meshing - PVM distributed , 88 parallel volume meshing - PVM local , 88 setting the CFX-Mesh preferences for ANSYS Workbench session, 103 setting the preferences using main menu, settings to enable Named Selections, 59 Verify Geometry - setting the tolerances and limits for the geometry checking , 43 y+, 77 overview, 1, 22 Details View, 21 GUI, Tree View, 17 tutorials, 119 P parameterization face checking - See also checking, 43 periodic pair extruded, 75 specifying the parameters to define a periodic pair, 73 periodicity description, 72 picking geometry elements using the Tools menu, plug-in mode See also reader mode, 25 point selecting, 13 point control description, 69 preview display mode, 98 face color, 98 inflated layers, 98 shine, 98 transparency, 98 preview group default preview group , 97 mesh statistics, 97 R N Named Selections description and guidelines, 59 O options auto backup options, 103 extruded 2D, 91 reader mode See also plug-in mode , 25 regions defining the location, description - See also requirements, 57 picking 2D regions and faces - using the selection rectangles, 57 relative error Release 12.1 - © 2009 SAS IP, Inc All rights reserved - Contains proprietary and confidential information of ANSYS, Inc and its subsidiaries and affiliates 245 Index specifying the curvature for an edge or face in terms of deviation, 67 removing - See also clearing; geometry; virtual topology, 44 requirements conditions on geometry for meshing needs, 27 creating an inflated boundary, 81 creating the geometry for meshing needs, 27 modeling guidelines to improve poorly-parameterized surfaces, 37 periodic pair - extruded 2D meshing , 94 specifying the location and topology of faces in the periodic pair, 74 restrictions creating a new body spacing, 63 meshing a thin surface topology, 35 Named Selections and Composite 2D Regions created in DesignModeler, 59 reverting mesh settings to the last saved database - See also clearing, rotation modes, free, 11 pitch, 11 roll, 11 toolbar, yaw, 11 ruler - See also toolbars; viewing, 15 S saving volume mesh, 101 selecting location, 12 point on a face, 13 using coordinates, 13 using graphics window, 12 using selection rectangles, 12 using tree view, 12 vertex, 13 selection filter edge, 13 face, 13 point, 13 region, 13 toolbar, 13 selection modes box select, 14 flood select, 14 toolbar, 14 selection rectangles - See also regions, 12 setting 246 length scale, shaded display - See also viewing, short edges - See also sliver, 44 sliver description of sliver factor - See also checking, 43 edge - checking the short edges, 42 face - checking the faces with high sliver factor, 43 removing the short edges - methods, 53 spacing, 63 body - specifying the background length scale for volume, 63 edge - specifying the mesh length scale on an edge, 65 face - specifying the mesh length scale on a face, 64 point - specifying the spacing attribute for volumetric controls, 68 relative error, 67 specifying the angular resolution, 67 status symbols status of items in the Tree View, 17 suppressing effects - viewing the bodies and parts in the Tree View , 45 objects - See also hiding, 19 surface mesh - See also meshing, 40 T tolerance checking the sliver edge, 42 consideration for virtual edges, 51 short edge limit, 43 sliver factor limit, 43 toolbars, geometry, 15 interrupt, 16 mesh edge length, 14 meshing, 16 rotation modes, selection modes, 14 triad and ruler, 14 zoom controls, total thickness considerations for inflation , 79 tree view hide and show - items in the Tree View , 20 highlighting the tree view items, 17 status symbols - status of items in the Tree View, 17 suppressing objects, 19 triad - See also toolbars; viewing, 15 triangle control description, 71 troubleshooting Release 12.1 - © 2009 SAS IP, Inc All rights reserved - Contains proprietary and confidential information of ANSYS, Inc and its subsidiaries and affiliates Index common queries related to the meshing, 107 error messages generated by CFX-Mesh, 107 valid and invalid values, 107 tutorials list of features, 122 mouse zoom, zoom to fit, U unsuppressing See also suppressing, 45 updating modifying the geometry, 25 V verifying - See also checking, 43 vertex selecting, 13 viewing error messages due to undesirable geometry, 41 mesh edge length, 14 pan, restoring the original window layout, rotate, shaded display with 3D edges or wireframe using the display toolbar, status symbols - status of items in the Tree View, 17 zoom - See also zoom controls, virtual edges description, 51 removing the short edges, 53 virtual faces description and example of, 48 virtual topology automatically edge merging tolerance, 103 automatically remove invalidated virtual cells, 103 creating a virtual faces, 48 creating the virtual edges, 51 defined, 47 guidelines for creating and adding virtual face and virtual edge, 47 visibility - See also selecting; viewing, 12 volume mesh generating, problems with degenerate geometry , 40 saving volume mesh, 101 W wireframe display - See also viewing, Z zoom controls box zoom, Release 12.1 - © 2009 SAS IP, Inc All rights reserved - Contains proprietary and confidential information of ANSYS, Inc and its subsidiaries and affiliates 247 248 Release 12.1 - © 2009 SAS IP, Inc All rights reserved - Contains proprietary and confidential information of ANSYS, Inc and its subsidiaries and affiliates ... in this section Meshing Overview Meshing Implementation in ANSYS Workbench Types of Meshing Conformal Meshing Between Parts Meshing Overview Philosophy The goal of meshing in ANSYS Workbench... This Panel at Meshing Startup This option controls whether the Meshing Options panel appears at startup of the Meshing application Meshing Implementation in ANSYS Workbench The meshing capabilities... system) Types of Meshing The following types of meshing are discussed in this section Meshing by Algorithm Meshing by Element Shape Meshing by Algorithm This section describes types of meshing in terms