ansys, inc. proprietary © 2004 ansys, inc. meshing techniques in ansys icem cfd 5.0 christian...
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ANSYS, Inc. Proprietary© 2004 ANSYS, Inc.
Meshing Techniques in Ansys ICEM CFD 5.0
Meshing Techniques in Ansys ICEM CFD 5.0
Christian NienhüserANSYS Germany
October 2004 CADFEM CZ User’s Meeting Slide 2
Contents
• New Graphic User Interface• Geometry import, clean up• Meshing Tools
– Surface meshing• Patch based • Patch independent
– Volume meshing• Tetrahedral• Hexahedral• Hybrid
• Outlook• Final remarks
October 2004 CADFEM CZ User’s Meeting Slide 3
Export to AnalysisOver 100 supported solver formats.
What is ANSYS ICEM CFD?
Direct CADCATIA, Pro/E, I-DEAS,
UG, SE, SW…
3rd Party CADIGES, ACIS, Parasolid…
Faceted Data
STL, Nastran, Patran, VRML…
ICEM CFDComplete CAE Pre-processing
• Create/Edit geometry • Generate mesh• Edit Mesh• Apply Poperties, B.C.’s
October 2004 CADFEM CZ User’s Meeting Slide 4
Classic GUI
ICEM CFD 4.2
Development Process
ICEM CFD 4.CFX AI*Environment 1.0
AI*Environment / ICEM CFD 5.0
AI*Environment 2.0ICEM CFD 4.3
Classic GUI ICEM CFD / AI*Environment 5.1
October 2004 CADFEM CZ User’s Meeting Slide 5
New Graphic User Interface
• User interface completely redesigned
• Integrates Med, Tetra, Prism, Hexa and Visual3
• Layout is– Clean– Modern– Intuitive
October 2004 CADFEM CZ User’s Meeting Slide 6
New Graphic User Interface
• Tabbed menus which follow the process
• Logical function groups
• Model tree– For display
control– Right-click
to access related options and operations
October 2004 CADFEM CZ User’s Meeting Slide 7
New Graphic User Interface
Selection and database management• Selection manager• Selection filters• Part selection by entity
• Blanking of specific entities• Improved subsets for geometry/mesh
– Easier methods of limiting data displayed
October 2004 CADFEM CZ User’s Meeting Slide 8
New Graphic User Interface
• Advanced help browser
• Quick-help
October 2004 CADFEM CZ User’s Meeting Slide 9
Geometry Import
Direct CADCATIA, Pro/E, I-DEAS,
UG, SolidWorks …
Direct CADCATIA, Pro/E, I-DEAS,
UG, SolidWorks …
CATIA
Unigraphics
Generic CADIGES, ACIS, DWG, STEP …
Generic CADIGES, ACIS, DWG, STEP …
SolidWorksSolidWorks
Faceted Data
STL, NASTRAN, Patran, VRML…
Faceted Data
STL, NASTRAN, Patran, VRML…
STL
ANSYS ICEM CFD
October 2004 CADFEM CZ User’s Meeting Slide 10
Geometry Import
Hexa for CATIA V5
October 2004 CADFEM CZ User’s Meeting Slide 11
Model Diagnosis and Repair
Build topology function• Tolerance is set automatically on import• Curves are extracted from surface model• Enables model diagnosis• Curves form basis for geometry repair
Imported CADImported CAD
October 2004 CADFEM CZ User’s Meeting Slide 12
Geometry tools
Repair•Topology checker to find problems in surface data•Surface closing•Surface retrimming/matching •Surface extension•Unsplit surface•Split by curvature•Modify surface normals•Bolt hole detection•Button detection•Fillet detection
Surface editing•Surface from curves•Driven surface•Swept surface•Revolved surface•Offset surface•Midsurface•Adjust thickness•Lofted surface
Body definitions•From connectivity•Point inside solid
Point creation•From screen•Explicit•Offset•Centerpoint•Between points•Endpoint•Intersection•Along curve•Projection to curve/surface
Curve creation•From points•Arc/Circle•Surface param•Intersection•Surface projection•Concatenation•Segmentation•Surface Boundary•Faceted curve tools
•Curtain surface•Surface trimming
•Merged surface
•Shrink wrapped surface
•Standard surfaces
•Faceted Surface tools
October 2004 CADFEM CZ User’s Meeting Slide 13
STL to B-Spline conversion
• Use geometry repair• Convert multiblock
mesh to b-spline• Reverse engineering
and legacy data support
Circle fom points
October 2004 CADFEM CZ User’s Meeting Slide 14
Quad surface meshing
• All-quadrilateral mesh
• Edge model
• CAD geometry
patch dependent
October 2004 CADFEM CZ User’s Meeting Slide 15
Quad Surface Meshing
• Mapping = 0 • Mapping = 0.2
Auto-structured meshing
October 2004 CADFEM CZ User’s Meeting Slide 16
Extensions
• Arbitrary boundary• Holes, prescribed
curves and prescribed points
• One/some transition triangles
• Auto-structured• Mesh refinement
October 2004 CADFEM CZ User’s Meeting Slide 17
Surface meshing enhancements
• Unstructured quad meshing algorithm integrated into Hexa mesher.
– Allows the easy creation of hybrid structured/unstructured meshes.
– Ideal mesh for crash and NVH.
• Initial auto blocking from CAD surfaces.
– Automatic merging of regions to create a better blocking.
– Geometry feature recognition in meshing.
October 2004 CADFEM CZ User’s Meeting Slide 18
Tetra meshing (Octree)
• Initial mesh of “Maximum size” elements fills a bounding box
October 2004 CADFEM CZ User’s Meeting Slide 19
Tetra meshing (Octree)
• Mesh is subdivided to meet specified sizes
• Nodes adjusted to conform to geometry
October 2004 CADFEM CZ User’s Meeting Slide 20
Tetra meshing (Octree)
• “Flood fill” process finds volume boundaries
October 2004 CADFEM CZ User’s Meeting Slide 21
Tetra meshing (Octree) Patch Independence
– Mesh “walks over” gaps, overlaps, holes, details– A perfect CAD model is not required– Greatly reduces the amount of required CAD cleanup
Surfaces near stamped label
Mesh “walks over” the detail
October 2004 CADFEM CZ User’s Meeting Slide 22
Tetra meshing (Octree)
• Improved: ‘bounding box’ by ‘geometry blow-up’
October 2004 CADFEM CZ User’s Meeting Slide 23
Tetra meshing: Improved Auto-Volume Detection
• Material points are automatically created – Multiple volumes are supported
October 2004 CADFEM CZ User’s Meeting Slide 24
Tetra meshing: Part-by-Part
• Enables assemblies to be meshed in batch as component parts
• Mesh is non-conformal
October 2004 CADFEM CZ User’s Meeting Slide 25
Tetra meshing: Improved Volume Mesh Controls
• Point, line, and volume density– Width parameter extends effect
• Volume defined by points or by bounding box around selected entities
Point density
October 2004 CADFEM CZ User’s Meeting Slide 26
Hybrid meshes
• Tet to hex converter
October 2004 CADFEM CZ User’s Meeting Slide 27
Prism meshing
• Prism layers in pure tetra meshes
October 2004 CADFEM CZ User’s Meeting Slide 28
Prism meshing
• Prism layers in hybrid meshes– Extrusion of
mixed quad/triangle meshes.
October 2004 CADFEM CZ User’s Meeting Slide 29
Hybrid meshing
• New hexahedral-dominant meshing
October 2004 CADFEM CZ User’s Meeting Slide 30
Hybrid meshing (outside of Hexa)
• Volume tetra -> add prisms -> convert interior to hexas.
• Surface tri/quad mesh -> add prisms -> fill with tets.
• Surface quad mesh -> add boundary hexas -> fill with hexas/tetras/pyramids/prisms
Easily in any order/any element type
October 2004 CADFEM CZ User’s Meeting Slide 31
Hexa meshing
Geometry Blocking Mesh
• Multi-block structured
October 2004 CADFEM CZ User’s Meeting Slide 32
Auto 2-D blocking approach
Free block
Mapped block
• Each Rectangular surface gets a mapped block.
• Arbitrary surfaces get free blocks.• Blocks are independent of surface
topology (morphable).• Geometry recognition is used to group
potentially problem surfaces.
October 2004 CADFEM CZ User’s Meeting Slide 33
Hex or hex dominant meshes
• Multiple automatic pathways to high quality all hex or hex dominant meshes.– Auto surface blocking followed by auto
volume blocking.
– Direct block decomposition method.
– Auto surface blocking into surface meshing into hex dominant volume meshing.
– Hexa tools can be used to assist either the surface blocking or the volume blocking.
• Better parametric association• Hybrid meshing framework
October 2004 CADFEM CZ User’s Meeting Slide 34
Auto blocking from surface blocking
• Start from CAD surfaces.
• Generate Auto 2-D blocks based on surfaces
• Generate Auto 3-D blocks by filling in 2-D blocks with Hex dominant mesher
• Automatically create mesh spacing and mesh with existing Hexa techniques.
• Results in a high-quality all hex mesh.
All Hex
October 2004 CADFEM CZ User’s Meeting Slide 35
True automatic blocking
Produces great blocking but sensitive to geometric details
October 2004 CADFEM CZ User’s Meeting Slide 36
Hex meshing: Hex dominant mesher
• Start from CAD geomety• Generate all quad surface mesh as
before• Automatically fills surface mesh with
uniform hex dominant mesh• User can then edit the hex dominant
mesh by automatic smoothing and mesh editing
HEXA_8 : 4849
PENTA_6 : 287
PYRA_5 : 640
TETRA_4 : 313
October 2004 CADFEM CZ User’s Meeting Slide 37
HEXA: System level
Hexa will do the bookkeeping to keep track of the connectivity of hybrid meshes.
• Structured blocks.• Extruded blocks
– All Quad– Quad + 1 Tri– Quad dominant– All Tri
• Unstructured blocks:– Filled by Tetra– Filled by Hex-Dominant mesher– Filled by Delaunay mesher.
October 2004 CADFEM CZ User’s Meeting Slide 38
Final remarks
• Thank you!
• Questions?