LSCFD: Meshing Tools for Open Source CFD â A Practical ... - CSC
LSCFD: Meshing Tools for Open Source CFD â A Practical ... - CSC
LSCFD: Meshing Tools for Open Source CFD â A Practical ... - CSC
Create successful ePaper yourself
Turn your PDF publications into a flip-book with our unique Google optimized e-Paper software.
<strong>LS<strong>CFD</strong></strong>:<strong>Meshing</strong> <strong>Tools</strong> <strong>for</strong> <strong>Open</strong> <strong>Source</strong> <strong>CFD</strong>– A <strong>Practical</strong> Point of ViewJuha Kortelainen
VTT TECHNICAL RESEARCH CENTRE OF FINLANDReport: <strong>Meshing</strong> <strong>Tools</strong> <strong>for</strong> <strong>Open</strong> <strong>Source</strong><strong>CFD</strong> – A <strong>Practical</strong> Point of View<strong>LS<strong>CFD</strong></strong> – <strong>Tools</strong> <strong>for</strong> Large Scale Computational Fluid DynamicsThe main objectives of the project:• Demonstrate and document the full chain of large scale <strong>CFD</strong> from meshgeneration to visualization using best available open source tools.• Remove some bottle-necks in the utilization of the tools <strong>for</strong> large scalecomputing. The bottle-necks are related, <strong>for</strong> example, to large scale meshgeneration, use of parallel preconditioners, and treatment of massivelyparallel data.• Implement Variational Multiscale Method (VMS) to massively parallelframework. The natural coding environment <strong>for</strong> the project will be the Elmerfinite element software which has also been mainly developed at <strong>CSC</strong>.• Transfer know-how to <strong>CFD</strong> community in general and special user groups inparticular. The means of knowledge transfer will be courses, seminars andreports. Most happenings will be organized around some particular softwarebut also generic large scale <strong>CFD</strong> theme will be considered.• Increase the use of supercomputing <strong>for</strong> computational fluid dynamics inFinland. Mainly it is hoped that the academic community would start usingthe large scale methods and this would eventually result also to increaseduse of large scale <strong>CFD</strong> in the industry.http://www.csc.fi/english/pages/lscfd/goals25.5.2009<strong>LS<strong>CFD</strong></strong>: <strong>Meshing</strong> <strong>Tools</strong> <strong>for</strong> <strong>Open</strong> <strong>Source</strong> <strong>CFD</strong> – A <strong>Practical</strong> Point of View :: Juha Kortelainen2
VTT TECHNICAL RESEARCH CENTRE OF FINLANDIntroduction and Scope• Survey on open source or low costtools <strong>for</strong> <strong>CFD</strong> pre-processing- Target <strong>CFD</strong> solver: <strong>Open</strong>FOAM(version 1.5)• Tested software:- SALOME version 3.2.6- SALOME version 4.1.4 (shortly)- Gmsh- <strong>Open</strong>FOAM SnappyHexMesh• Focus on industrial applications- Strategy: Use inexpensivecomputational tools <strong>for</strong> massivecomputations- No limits in number of simultaneouslicenses- Short calendar time <strong>for</strong> computations25.5.2009<strong>LS<strong>CFD</strong></strong>: <strong>Meshing</strong> <strong>Tools</strong> <strong>for</strong> <strong>Open</strong> <strong>Source</strong> <strong>CFD</strong> – A <strong>Practical</strong> Point of View :: Juha Kortelainen3
VTT TECHNICAL RESEARCH CENTRE OF FINLANDWhere is the Beef in Using <strong>Open</strong> <strong>Source</strong> <strong>Tools</strong>?Design Design study studyCase Case #1 #1 Case Case #2 #2 Case Case #... #... Case Case #N #NResults ResultsOptimisationParametercomparisonCase Case #1 #1Case Case #1 #1Case Case #2 #2Case Case #... #...Case Case #N #NResults ResultsManyComputationalcasesComputationalconstraint:simultaneouslicensesTime savingTime25.5.2009<strong>LS<strong>CFD</strong></strong>: <strong>Meshing</strong> <strong>Tools</strong> <strong>for</strong> <strong>Open</strong> <strong>Source</strong> <strong>CFD</strong> – A <strong>Practical</strong> Point of View :: Juha Kortelainen4
VTT TECHNICAL RESEARCH CENTRE OF FINLAND<strong>Meshing</strong> and Mesh Types• Mesh types and the process ingeneral- For <strong>CFD</strong> structured hexahedral meshis beneficial in general often difficultto create, manual meshing- Unstructured tetrahedral mesh can begenerated automatically, but mesh isusually not optimal <strong>for</strong> <strong>CFD</strong> fast tocreate and relatively robust, possiblecomputational problems• Most of the meshers produceunstructured tetrahedral mesh• Question of overall process time- Automatic meshing: Is the time that islost in solving won in pre-processing?- Mesh quality and convergence?25.5.2009<strong>LS<strong>CFD</strong></strong>: <strong>Meshing</strong> <strong>Tools</strong> <strong>for</strong> <strong>Open</strong> <strong>Source</strong> <strong>CFD</strong> – A <strong>Practical</strong> Point of View :: Juha Kortelainen5
VTT TECHNICAL RESEARCH CENTRE OF FINLANDHow did We Test?• Industrial test case was selected- Wärtsilä W20V32SG engine, part ofexhaust manifold• All the preparations were donewith tested tools• Objective: to mesh the test caseso that it is usable <strong>for</strong> <strong>CFD</strong>simulation with <strong>Open</strong>FOAM25.5.2009<strong>LS<strong>CFD</strong></strong>: <strong>Meshing</strong> <strong>Tools</strong> <strong>for</strong> <strong>Open</strong> <strong>Source</strong> <strong>CFD</strong> – A <strong>Practical</strong> Point of View :: Juha Kortelainen6
VTT TECHNICAL RESEARCH CENTRE OF FINLANDSimplified Process Flow <strong>for</strong>Industrial <strong>CFD</strong> Pre-ProcessingDesign geometryin CAD systemMesh processingGeometryimportDesign geometry in <strong>CFD</strong>pre-processing systemSimplified and healedgeometry in pre-processingStructuredmeshMeshtopologydesignUnstructuredmeshGeometrymanipulationGrid density(global/local)<strong>Meshing</strong>Use of AMRGeometry processingComputational meshComputationsResultsFinal productioncomputational mesh25.5.2009<strong>LS<strong>CFD</strong></strong>: <strong>Meshing</strong> <strong>Tools</strong> <strong>for</strong> <strong>Open</strong> <strong>Source</strong> <strong>CFD</strong> – A <strong>Practical</strong> Point of View :: Juha Kortelainen7
VTT TECHNICAL RESEARCH CENTRE OF FINLANDSALOMEhttp://www.salome-plat<strong>for</strong>m.org/• Tested version 3.2.6; shortly introduced version 4.1.4• The most extensive pre-processor of tested tools- Geometry import in ACIS, SALOME native BREP, IGES, and STEP (uses <strong>Open</strong>CASCADE)- Geometry creation and manipulation- <strong>Meshing</strong> in principle <strong>for</strong> structured and unstructured mesh types; structured mesh creationvery difficult so only unstructured tetrahedral mesh was tested- Mesh quality checking and visualisation- Export in DAT (ASCII table <strong>for</strong>mat), MED, I-deas UNV, and STL (surface mesh only)• Version 3.2.6 had many annoying bugs and features, most of them werefixed in version 4.1.4• The created default tetrahedral mesh was not very suitable <strong>for</strong> <strong>CFD</strong>(optimised <strong>for</strong> FEM)• Massive and complex software, available only <strong>for</strong> Linux (and UNIX)• License: GNU Lesser General Public License (LGPL)25.5.2009<strong>LS<strong>CFD</strong></strong>: <strong>Meshing</strong> <strong>Tools</strong> <strong>for</strong> <strong>Open</strong> <strong>Source</strong> <strong>CFD</strong> – A <strong>Practical</strong> Point of View :: Juha Kortelainen8
VTT TECHNICAL RESEARCH CENTRE OF FINLAND25.5.2009<strong>LS<strong>CFD</strong></strong>: <strong>Meshing</strong> <strong>Tools</strong> <strong>for</strong> <strong>Open</strong> <strong>Source</strong> <strong>CFD</strong> – A <strong>Practical</strong> Point of View :: Juha Kortelainen9
VTT TECHNICAL RESEARCH CENTRE OF FINLANDGmshhttp://geuz.org/gmsh/• Tested version 2.3.0 (not mentioned in the report)• A lightweight pre-processor compared to SALOME- Geometry import in IGES, STEP, BREP, and gmsh native GEO <strong>for</strong>mat (uses <strong>Open</strong>CASCADE)- Only limited geometry creation and manipulation capabilities; imported CAD geometriescould not be modified in gmsh- <strong>Meshing</strong> only <strong>for</strong> unstructured tetrahedral mesh (netgen and tetgen routines)- Mesh quality checking and visualisation- Mesh export in I-deas UNV, VTK, MED, Medit, Nastran bulk data, Plot3D structuredmesh, STL (surface mesh), VRML (surface mesh), DIFFPACK 3D mesh <strong>for</strong>mat• Imported 3D solid geometry handling was still unstable and buggy• The created default tetrahedral mesh was relatively suitable <strong>for</strong><strong>CFD</strong>• Software is available <strong>for</strong> Linux (UNIX) and Windows systems• License: GNU General Public License (GPL)25.5.2009<strong>LS<strong>CFD</strong></strong>: <strong>Meshing</strong> <strong>Tools</strong> <strong>for</strong> <strong>Open</strong> <strong>Source</strong> <strong>CFD</strong> – A <strong>Practical</strong> Point of View :: Juha Kortelainen10
VTT TECHNICAL RESEARCH CENTRE OF FINLAND25.5.2009<strong>LS<strong>CFD</strong></strong>: <strong>Meshing</strong> <strong>Tools</strong> <strong>for</strong> <strong>Open</strong> <strong>Source</strong> <strong>CFD</strong> – A <strong>Practical</strong> Point of View :: Juha Kortelainen11
VTT TECHNICAL RESEARCH CENTRE OF FINLAND<strong>Open</strong>FOAM SnappyHexMeshhttp://www.opencfd.co.uk/openfoam/• Functionality included into <strong>Open</strong>FOAM package, tested version 1.5• Different approach to meshing- Automatic meshing of given geometry using unstructured mesh with hexahedral cells- Geometry import in STL surface models- Mesh refinement on surfaces- Many options to control the quality of the created mesh difficult <strong>for</strong> a beginner- Mesh is created using a batch run (command line)- The routine can not handle well sharp corners and edges method is not suitable <strong>for</strong> allindustrial or research cases• Routine and tools seemed robust and relatively fast• Mesh modifications (e.g. mesh density) are quite easy to do• Available <strong>for</strong> Linux (UNIX) systems• License: GNU General Public License (GPL) (part of <strong>Open</strong>FOAM)25.5.2009<strong>LS<strong>CFD</strong></strong>: <strong>Meshing</strong> <strong>Tools</strong> <strong>for</strong> <strong>Open</strong> <strong>Source</strong> <strong>CFD</strong> – A <strong>Practical</strong> Point of View :: Juha Kortelainen12
VTT TECHNICAL RESEARCH CENTRE OF FINLANDLevel 0 Level 1 Level 225.5.2009<strong>LS<strong>CFD</strong></strong>: <strong>Meshing</strong> <strong>Tools</strong> <strong>for</strong> <strong>Open</strong> <strong>Source</strong> <strong>CFD</strong> – A <strong>Practical</strong> Point of View :: Juha Kortelainen13
VTT TECHNICAL RESEARCH CENTRE OF FINLANDOriginalgeometrySnappyHexMeshgeometry25.5.2009<strong>LS<strong>CFD</strong></strong>: <strong>Meshing</strong> <strong>Tools</strong> <strong>for</strong> <strong>Open</strong> <strong>Source</strong> <strong>CFD</strong> – A <strong>Practical</strong> Point of View :: Juha Kortelainen14
VTT TECHNICAL RESEARCH CENTRE OF FINLANDConclusions and Summary• Pre-processing is still very time consuming phase in <strong>CFD</strong> and FEM process• Step of getting started quite high, limited documentation and tutorials• None of the tested software separately were successful in the whole preprocessingprocess• SALOME and gmsh together offered relatively good results <strong>for</strong> <strong>CFD</strong> preprocessing;still geometry manipulation is difficult• Creation of structured hexahedral mesh is far too difficult• <strong>Open</strong>FOAM SnappyHexMesh is very promising method but not yet ready <strong>for</strong>industrial use (problems with edge and corner meshing)• Integration to industrial design systems and design process? Still more work is needed to have an industrial strength open sourcepre-processor <strong>for</strong> <strong>CFD</strong> and FEM25.5.2009<strong>LS<strong>CFD</strong></strong>: <strong>Meshing</strong> <strong>Tools</strong> <strong>for</strong> <strong>Open</strong> <strong>Source</strong> <strong>CFD</strong> – A <strong>Practical</strong> Point of View :: Juha Kortelainen15
VTT TECHNICAL RESEARCH CENTRE OF FINLANDWhat Next?• What is the industry’s interest in open source computational tools?• What should be done? What is the priority <strong>for</strong> tasks?• Co-operation? Forum <strong>for</strong> co-operation? Partners? Funding?• How to integrate into a industrial design and developmentprocess?Who will catch the ball?25.5.2009<strong>LS<strong>CFD</strong></strong>: <strong>Meshing</strong> <strong>Tools</strong> <strong>for</strong> <strong>Open</strong> <strong>Source</strong> <strong>CFD</strong> – A <strong>Practical</strong> Point of View :: Juha Kortelainen16
Change language