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3D simulations OpenFoam running too low(more 1 000 000 elements) Suggestion speed up? |
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March 31, 2017, 07:39 |
3D simulations OpenFoam running too low(more 1 000 000 elements) Suggestion speed up?
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Join Date: May 2013
Posts: 21
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Hi OpenFoam people!
I am simulating blood flow in 3D arteries using OpenFoam code. Previous simulations are converging much more faster using the multi-grid solver GAMG for Pressure. And, I also used a bounded scheme for div(phi, U) to avoid divergence. The 3D blood flow simulations using a simple model to define blood rheology and conservative equations implemented in OpenFoam, are running faster (only 1 day!) for more than 1 000 000 elements. Also, the results are accurate since they are coincident with that obtained through the comercial code ANSYS. However.... I also implemented a complex blood rheology to define in a more accurate way the blood physical properties. This properties are defined through a constitutive equation, which conservative equations depend on this constitutive equation. So, since OpenFoam is an Open Source Code, I modified the conservative equations and implemented the constitutive equation (defining blood rheology more correctly). This code was already validated in 2D dimension of the artery (with much less elements!). In this way... My question is.... I want to simulate the previous case, in 3D dimension with more than 1 000 000 elements, faster. The simulations are too low... (Perhaps more than 1 week to converge! ) Since, now, this code is more complex than the first one. Do you have any suggestion (modify any method or parameter) for that simulations can run a lot more faster, for this case, and do not have the risk to diverge? ************************************************* "boundary" file: ( wall-interior { type wall; nFaces 59205; startFace 1248069; } inlet_lca { type patch; nFaces 2625; startFace 1307274; } outlet_lda { type patch; nFaces 2130; startFace 1309899; } outlet_lcx { type patch; nFaces 2214; startFace 1312029; } ) ************************************************** The "controlDict" file than I am using is: application elasticshearthinFluidFoam; startFrom latestTime; startTime 0; stopAt endTime; endTime 3.0; deltaT 0.0005; writeControl adjustableRunTime; writeInterval 0.01; purgeWrite 0; writeFormat ascii; writePrecision 6; writeCompression uncompressed; timeFormat general; timePrecision 6; graphFormat raw; runTimeModifiable yes; adjustTimeStep on; maxCo 0.8; maxDeltaT 0.001; ************************************************** *** The "fvSchemes" file is: ddtSchemes { default Euler; } gradSchemes { default Gauss linear; grad(p) Gauss linear; grad(U) Gauss linear; } divSchemes { default none; div(phi,U) Gauss SFCD; div(phi,detAfirst) Gauss Minmod; div(phi,detAsecond) Gauss Minmod; div(phi,detAthird) Gauss Minmod; div(phi,detAfourth) Gauss Minmod; div(phi,taufirst) Gauss Minmod; div(phi,tausecond) Gauss Minmod; div(phi,tauthird) Gauss Minmod; div(phi,taufourth) Gauss Minmod; div(tau) Gauss linear; } laplacianSchemes { default none; laplacian(etaPEff,U) Gauss linear corrected; laplacian(etaPEff+etaS,U) Gauss linear corrected; laplacian((1|A(U)),p) Gauss linear corrected; } interpolationSchemes { default linear; interpolate(HbyA) linear; } snGradSchemes { default corrected; } fluxRequired { default no; p; } ************************************************* The "fvSolution" file is: solvers { p { solver GAMG; preconditioner { // preconditioner Cholesky; preconditioner FDIC; cycle W-cycle; policy AAMG; nPreSweeps 0; nPostSweeps 2; groupSize 4; minCoarseEqns 20; nMaxLevels 100; scale off; smoother ILU; } tolerance 1e-05; relTol 0; minIter 0; maxIter 800; agglomerator faceAreaPair; nCellsInCoarsestLevel 100; mergeLevels 1; smoother GaussSeidel; } U { solver BICCG; preconditioner { preconditioner DILU; } tolerance 1e-6; relTol 0; minIter 0; maxIter 1000; agglomerator faceAreaPair; nCellsInCoarsestLevel 4; mergeLevels 1; smoother DILUGaussSeidel; } detAfirst { solver BICCG; preconditioner { preconditioner DILU; } tolerance 1e-6; relTol 0; minIter 0; maxIter 1000; agglomerator faceAreaPair; nCellsInCoarsestLevel 4; mergeLevels 1; smoother DILUGaussSeidel; } detAsecond { solver BICCG; preconditioner { preconditioner DILU; } tolerance 1e-6; relTol 0; minIter 0; maxIter 1000; agglomerator faceAreaPair; nCellsInCoarsestLevel 4; mergeLevels 1; smoother DILUGaussSeidel; } detAthird { solver BICCG; preconditioner { preconditioner DILU; } tolerance 1e-6; relTol 0; minIter 0; maxIter 1000; agglomerator faceAreaPair; nCellsInCoarsestLevel 4; mergeLevels 1; smoother DILUGaussSeidel; } detAfourth { solver BICCG; preconditioner { preconditioner DILU; } tolerance 1e-6; relTol 0; minIter 0; maxIter 1000; agglomerator faceAreaPair; nCellsInCoarsestLevel 4; mergeLevels 1; smoother DILUGaussSeidel; } taufirst { solver BICCG; preconditioner { preconditioner DILU; } tolerance 1e-6; relTol 0; minIter 0; maxIter 1000; agglomerator faceAreaPair; nCellsInCoarsestLevel 4; mergeLevels 1; smoother DILUGaussSeidel; } tausecond { solver BICCG; preconditioner { preconditioner DILU; } tolerance 1e-6; relTol 0; minIter 0; maxIter 1000; agglomerator faceAreaPair; nCellsInCoarsestLevel 4; mergeLevels 1; smoother DILUGaussSeidel; } tauthird { solver BICCG; preconditioner { preconditioner DILU; } tolerance 1e-6; relTol 0; minIter 0; maxIter 1000; agglomerator faceAreaPair; nCellsInCoarsestLevel 4; mergeLevels 1; smoother DILUGaussSeidel; } taufourth { solver BICCG; preconditioner { preconditioner DILU; } tolerance 1e-6; relTol 0; minIter 0; maxIter 1000; agglomerator faceAreaPair; nCellsInCoarsestLevel 4; mergeLevels 1; smoother DILUGaussSeidel; }; } PISO { nCorrectors 1; nNonOrthogonalCorrectors 2; pRefCell 200; pRefValue 10000; // nCorrectors 2; // nNonOrthogonalCorrectors 0; // pRefCell 0; // pRefValue 0; } relaxationFactors { p 0.3; U 0.5; detAfirst 0.3; detAsecond 0.3; detAthird 0.3; detAfourth 0.3; taufirst 0.3; tausecond 0.3; tauthird 0.3; taufourth 0.3; // p 0.3; // U 0.5; // tau 0.3; } ************************************************** ********* Apparently, the simulations are converging with this process, but I think that I will wait one week for the results... Do someone suggest to modify any parameter to run faster and with convergence? I will be greatful! Thank you very much! |
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