# pimpleDyMFoam diverging

 Register Blogs Members List Search Today's Posts Mark Forums Read

 March 31, 2010, 12:51 pimpleDyMFoam diverging #1 Member   Join Date: May 2009 Posts: 52 Rep Power: 10 Hello everyone, I am using pimpleDyMFoam with a custom dynamicFvMesh to solve for the motion of a 2D circular cylinder with 1DOF (heave) with the standard SA model. I am having issues with the solver diverging after several time steps. The time step keeps decreasing to meet the maxCo criterion, while the actual Co oscillates and eventually blows up, resulting in the solver crashing. Here is a part of the log: Code: ```Courant Number mean: 0.181987 max: 57.4844 deltaT = 3.73109e-10 Time = 0.00065686 Pressure force = (-5.77062e+11 -1.75305e+13 1.484e-05) Viscous force = (1.06804e+10 -3.28055e+09 4.6907e-05) Total force = (-5.66381e+11 -1.75338e+13 6.1747e-05) Pressure force = (-5.77062e+11 -1.75305e+13 1.484e-05) Viscous force = (1.06804e+10 -3.28055e+09 4.6907e-05) Total force = (-5.66381e+11 -1.75338e+13 6.1747e-05) new force= (-5.66381e+11 -1.75338e+13 6.1747e-05) damping force= (0 111.291 0) spring force= (0 0.19882 0) displace component= 0.0298225 DILUPBiCG: Solving for Ux, Initial residual = 0.00118393, Final residual = 6.46833e-07, No Iterations 1 DILUPBiCG: Solving for Uy, Initial residual = 0.000226988, Final residual = 1.6964e-07, No Iterations 1 DICPCG: Solving for p, Initial residual = 0.936208, Final residual = 9.29128e-07, No Iterations 303 time step continuity errors : sum local = 2.91692e-12, global = 3.30302e-14, cumulative = 2.10666e-12 DILUPBiCG: Solving for Ux, Initial residual = 0.0011032, Final residual = 2.14598e-08, No Iterations 1 DILUPBiCG: Solving for Uy, Initial residual = 0.00026622, Final residual = 5.22804e-09, No Iterations 1 DICPCG: Solving for p, Initial residual = 0.474501, Final residual = 9.38896e-07, No Iterations 298 time step continuity errors : sum local = 4.10823e-12, global = 4.30266e-14, cumulative = 2.14969e-12 DILUPBiCG: Solving for nuTilda, Initial residual = 2.76369e-06, Final residual = 2.76369e-06, No Iterations 0 ExecutionTime = 24.02 s ClockTime = 24 s Courant Number mean: 0.0012636 max: 0.200559 deltaT = 4.47731e-10 Time = 0.00065686 Pressure force = (3.14683e+13 2.90887e+14 -0.000464347) Viscous force = (6.73597e+09 -3.07824e+09 4.73848e-06) Total force = (3.1475e+13 2.90884e+14 -0.000459609) Pressure force = (3.14683e+13 2.90887e+14 -0.000464347) Viscous force = (6.73597e+09 -3.07824e+09 4.73848e-06) Total force = (3.1475e+13 2.90884e+14 -0.000459609) new force= (3.1475e+13 2.90884e+14 -0.000459609) damping force= (0 96.883 0) spring force= (0 0.200467 0) displace component= 0.0309868 DILUPBiCG: Solving for Ux, Initial residual = 0.016213, Final residual = 8.38248e-08, No Iterations 2 DILUPBiCG: Solving for Uy, Initial residual = 0.0037189, Final residual = 6.18129e-07, No Iterations 1 DICPCG: Solving for p, Initial residual = 0.614507, Final residual = 8.80742e-07, No Iterations 344 time step continuity errors : sum local = 2.19871e-12, global = 1.48693e-14, cumulative = 2.16456e-12 DILUPBiCG: Solving for Ux, Initial residual = 0.0376498, Final residual = 4.48819e-09, No Iterations 2 DILUPBiCG: Solving for Uy, Initial residual = 0.00476686, Final residual = 1.9605e-06, No Iterations 1 DICPCG: Solving for p, Initial residual = 0.494856, Final residual = 9.71665e-07, No Iterations 320 time step continuity errors : sum local = 8.84475e-12, global = 5.15065e-14, cumulative = 2.21606e-12 DILUPBiCG: Solving for nuTilda, Initial residual = 1.94363e-05, Final residual = 1.35167e-08, No Iterations 1 bounding nuTilda, min: -1.48587e-17 max: 3.92394 average: 0.00253206 ExecutionTime = 26.15 s ClockTime = 26 s Courant Number mean: 0.00577774 max: 0.207404 deltaT = 5.37277e-10 Time = 0.000656861 Pressure force = (2.07155e+09 -5.18228e+15 0.0122243) Viscous force = (2.52242e+09 -1.35877e+11 5.65746e-05) Total force = (4.59397e+09 -5.18242e+15 0.0122809) Pressure force = (2.07155e+09 -5.18228e+15 0.0122243) Viscous force = (2.52242e+09 -1.35877e+11 5.65746e-05) Total force = (4.59397e+09 -5.18242e+15 0.0122809) new force= (4.59397e+09 -5.18242e+15 0.0122809) damping force= (0 383.723 0) spring force= (0 0.208293 0) displace component= 0.0100557 DILUPBiCG: Solving for Ux, Initial residual = 0.207082, Final residual = 3.86788e-06, No Iterations 3 DILUPBiCG: Solving for Uy, Initial residual = 0.139973, Final residual = 2.91468e-06, No Iterations 3 DICPCG: Solving for p, Initial residual = 0.98152, Final residual = 9.09526e-07, No Iterations 333 time step continuity errors : sum local = 2.52805e-11, global = 4.02247e-14, cumulative = 2.25629e-12 DILUPBiCG: Solving for Ux, Initial residual = 0.40134, Final residual = 6.16425e-06, No Iterations 4 DILUPBiCG: Solving for Uy, Initial residual = 0.0181964, Final residual = 2.29782e-06, No Iterations 3 DICPCG: Solving for p, Initial residual = 0.981988, Final residual = 8.49443e-07, No Iterations 293 time step continuity errors : sum local = 1.21941e-09, global = 2.49295e-12, cumulative = 4.74924e-12 DILUPBiCG: Solving for nuTilda, Initial residual = 0.000310185, Final residual = 9.04832e-06, No Iterations 1 bounding nuTilda, min: -0.402278 max: 67.8727 average: 0.0384613 ExecutionTime = 28.24 s ClockTime = 28 s Courant Number mean: 0.11094 max: 21.5535 #0 Foam::error::printStack(Foam::Ostream&) in "/home/greg/OpenFOAM/OpenFOAM-1.6.x/lib/linuxGccDPOpt/libOpenFOAM.so" #1 Foam::sigFpe::sigFpeHandler(int) in "/home/greg/OpenFOAM/OpenFOAM-1.6.x/lib/linuxGccDPOpt/libOpenFOAM.so" #2 Uninterpreted: #3 Foam::Time::adjustDeltaT() in "/home/greg/OpenFOAM/OpenFOAM-1.6.x/lib/linuxGccDPOpt/libOpenFOAM.so" #4 Foam::Time::setDeltaT(double) in "/home/greg/OpenFOAM/OpenFOAM-1.6.x/lib/linuxGccDPOpt/libOpenFOAM.so" #5 main in "/home/greg/OpenFOAM/OpenFOAM-1.6.x/applications/bin/linuxGccDPOpt/pimpleDyMFoam" #6 __libc_start_main in "/lib/tls/i686/cmov/libc.so.6" #7 _start at /build/buildd/eglibc-2.10.1/csu/../sysdeps/i386/elf/start.S:122 Floating point exception``` I have experimented with PIMPLE settings, and under-relaxation. My current settings in fvSolution are: Code: ```PIMPLE { nOuterCorrectors 2; nCorrectors 1; nNonOrthogonalCorrectors 0; pRefCell 0; pRefValue 0; } relaxationFactors { U 0.7; p 0.2; nuTilda 0.7; }``` And my fvSchemes: Code: ```ddtSchemes { default Euler; } gradSchemes { default Gauss linear; grad(p) Gauss linear; grad(U) Gauss linear; } divSchemes { default Gauss QUICK phi; // div(phi,U) Gauss limitedLinear 1; div(phi,U) Gauss upwind; div(phi,k) Gauss limitedLinear 1; div(phi,epsilon) Gauss limitedLinear 1; div(phi,R) Gauss limitedLinear 1; div(R) Gauss linear; div(phi,nuTilda) Gauss limitedLinear 1; div((nuEff*dev(grad(U).T()))) Gauss linear; } laplacianSchemes { default none; laplacian(nu,U) Gauss linear corrected; laplacian(nuEff,U) Gauss linear corrected; laplacian((1|A(U)),p) Gauss linear corrected; laplacian(DkEff,k) Gauss linear corrected; laplacian(DepsilonEff,epsilon) Gauss linear corrected; laplacian(DREff,R) Gauss linear corrected; laplacian(DnuTildaEff,nuTilda) Gauss linear corrected; laplacian(rAU,pcorr) Gauss linear corrected; laplacian(rAU,p) Gauss linear corrected; } interpolationSchemes { default linear; interpolate(U) linear; } snGradSchemes { default corrected; } fluxRequired { default no; p; }``` I'd appreciate any hints. -Greg

 March 28, 2012, 16:21 #2 New Member   Thomas Reviol Join Date: Jul 2011 Location: Germany, Kaiserslautern Posts: 27 Rep Power: 8 Hi Greg, try to run "unset FOAM_SIGFPE" in the commandline, before you run your job. Regards Thomas

 April 2, 2012, 14:24 #3 Member   Joe Join Date: Dec 2011 Location: Groton, CT Posts: 67 Rep Power: 8 Greg, Were you able to get this working? Would you mind posting your dynamic mesh dictionary? I'm interested in seeing it. Thanks, Joe

 April 2, 2012, 15:20 #4 Member   Join Date: May 2009 Posts: 52 Rep Power: 10 Hi Thomas and Joe, I was able to get the case working but it has been a while. Unfortunately I had a different workstation at that time and those case setups have not made the move, so I am unable to share the dynamic mesh dict with you. Sorry! Greg

 April 2, 2012, 22:51 #5 Member   Elh. A2. BAH Join Date: Jan 2012 Posts: 64 Rep Power: 8 Hey gfillip, I understand you no longer have the data, but do you remember a bit of what you did to solve the problem. I am running into similar difficulties where the Courant number keeps increasing until the job crashes. Here are my few lines of my log file: -------------------------------- Courant Number mean: 0.0553216 max: 1.49585 deltaT = 1e-05 Time = 7e-05 solidBodyMotionFunctions::rotatingMotion::transfor mation(): Time = 7e-05 transformation: ((0 0 0) (1 (0 0 0.00071295))) AMI: Creating addressing and weights between 152 source faces and 152 target faces AMI: Patch source weights min/max/average = 1.00045, 1.00059, 1.00051 AMI: Patch target weights min/max/average = 1.00027, 1.00041, 1.00034 PIMPLE: iteration 1 smoothSolver: Solving for Ux, Initial residual = 0.821499, Final residual = 0.0529954, No Iterations 2 smoothSolver: Solving for Uy, Initial residual = 0.772528, Final residual = 0.0435714, No Iterations 2 smoothSolver: Solving for Uz, Initial residual = 0.889394, Final residual = 0.0573016, No Iterations 3 GAMG: Solving for p, Initial residual = 0.927555, Final residual = 0.00793319, No Iterations 3 time step continuity errors : sum local = 0.00232858, global = 1.09112e-05, cumulative = 4.39653e-05 PIMPLE: iteration 2 smoothSolver: Solving for Ux, Initial residual = 0.624835, Final residual = 0.0579445, No Iterations 8 smoothSolver: Solving for Uy, Initial residual = 0.528869, Final residual = 0.0500303, No Iterations 7 smoothSolver: Solving for Uz, Initial residual = 0.667562, Final residual = 0.0371676, No Iterations 4 GAMG: Solving for p, Initial residual = 0.921425, Final residual = 0.00829498, No Iterations 2 time step continuity errors : sum local = 0.0183302, global = 0.000417751, cumulative = 0.000461716 PIMPLE: iteration 3 DILUPBiCG: Solving for Ux, Initial residual = 0.469402, Final residual = 0.00155559, No Iterations 1001 DILUPBiCG: Solving for Uy, Initial residual = 0.456055, Final residual = 0.00192389, No Iterations 1001 DILUPBiCG: Solving for Uz, Initial residual = 0.657918, Final residual = 7.2394e-07, No Iterations 26 GAMG: Solving for p, Initial residual = 0.940662, Final residual = 9.79822e-07, No Iterations 23 time step continuity errors : sum local = 5.83896e-06, global = -5.30525e-07, cumulative = 0.000461185 DILUPBiCG: Solving for epsilon, Initial residual = 0.989478, Final residual = 10537.6, No Iterations 1001 bounding epsilon, min: -1.28949e+18 max: 9.22403e+17 average: -3.22331e+14 DILUPBiCG: Solving for k, Initial residual = 1.42853e-05, Final residual = 6.87541e-07, No Iterations 30 bounding k, min: -1.84393e+10 max: 2.85172e+12 average: 1.06974e+10 ExecutionTime = 12.17 s ClockTime = 13 s forces output: forces(pressure, viscous)((-2.16039e+11 -1.76242e+12 2.33002e+07) (-4.46086e+07 -2.83529e+08 5.60693e+07)) moment(pressure, viscous)((-7.72514e+11 9.4704e+10 4.1255e+10) (-9.58347e+07 1.70477e+07 1.15609e+07)) Courant Number mean: 4.69634 max: 8810.84 deltaT = 2.26963e-09 Time = 7.00023e-05 solidBodyMotionFunctions::rotatingMotion::transfor mation(): Time = 7.00023e-05 transformation: ((0 0 -8.67362e-19) (1 (0 0 0.000712973))) AMI: Creating addressing and weights between 152 source faces and 152 target faces AMI: Patch source weights min/max/average = 1.00045, 1.00059, 1.00051 AMI: Patch target weights min/max/average = 1.00027, 1.00041, 1.00034 PIMPLE: iteration 1 smoothSolver: Solving for Ux, Initial residual = 0.924264, Final residual = 0.0530127, No Iterations 2 smoothSolver: Solving for Uy, Initial residual = 0.641598, Final residual = 0.0386788, No Iterations 2 smoothSolver: Solving for Uz, Initial residual = 0.921792, Final residual = 0.0461483, No Iterations 2 GAMG: Solving for p, Initial residual = 1, Final residual = 5705.13, No Iterations 50 time step continuity errors : sum local = 9.40062e+08, global = 3.78949e+07, cumulative = 3.78949e+07 PIMPLE: iteration 2 smoothSolver: Solving for Ux, Initial residual = 1, Final residual = 0.0224152, No Iterations 1 smoothSolver: Solving for Uy, Initial residual = 1, Final residual = 0.0293676, No Iterations 1 smoothSolver: Solving for Uz, Initial residual = 0.00299007, Final residual = 6.31039e-05, No Iterations 1 GAMG: Solving for p, Initial residual = 0.595319, Final residual = 9.86458e-05, No Iterations 1 time step continuity errors : sum local = 3.27194e+16, global = 4.33629e+15, cumulative = 4.33629e+15 PIMPLE: iteration 3 DILUPBiCG: Solving for Ux, Initial residual = 0.999996, Final residual = 5.86893e-07, No Iterations 28 DILUPBiCG: Solving for Uy, Initial residual = 0.999998, Final residual = 7.80082e-07, No Iterations 20 DILUPBiCG: Solving for Uz, Initial residual = 0.000201204, Final residual = 9.98882e-07, No Iterations 5 GAMG: Solving for p, Initial residual = 0.879029, Final residual = 7.05858e-07, No Iterations 47 time step continuity errors : sum local = 4.76118e+19, global = -8.01772e+18, cumulative = -8.01339e+18 DILUPBiCG: Solving for epsilon, Initial residual = 1, Final residual = 48876.6, No Iterations 1001 bounding epsilon, min: -1.7324e+51 max: 2.47572e+51 average: 5.46302e+48 DILUPBiCG: Solving for k, Initial residual = 1, Final residual = 6.79817e-07, No Iterations 96 bounding k, min: -1.36796e+48 max: 7.09554e+59 average: 6.62561e+56 ExecutionTime = 15.72 s ClockTime = 16 s forces output: forces(pressure, viscous)((5.96091e+57 4.44151e+57 3.98466e+52) (3.53788e+57 -2.92522e+58 1.66546e+57)) moment(pressure, viscous)((2.01323e+57 -2.60251e+57 -1.10323e+57) (-1.21739e+58 -1.87448e+57 -3.42054e+57)) Courant Number mean: 2.99449e+25 max: 3.21959e+28 deltaT = 1.40989e-37 --> FOAM Warning : From function Time:perator++() in file db/Time/Time.C at line 1010 Increased the timePrecision from 6 to 7 to distinguish between timeNames at time 7.00023e-05 Time = 7.000227e-05 solidBodyMotionFunctions::rotatingMotion::transfor mation(): Time = 7.00023e-05 transformation: ((0 0 -8.67362e-19) (1 (0 0 0.000712973))) AMI: Creating addressing and weights between 152 source faces and 152 target faces AMI: Patch source weights min/max/average = 1.00045, 1.00059, 1.00051 AMI: Patch target weights min/max/average = 1.00027, 1.00041, 1.00034 PIMPLE: iteration 1 smoothSolver: Solving for Ux, Initial residual = 0.904795, Final residual = 0.0198399, No Iterations 2 smoothSolver: Solving for Uy, Initial residual = 0.920089, Final residual = 0.00357272, No Iterations 1 smoothSolver: Solving for Uz, Initial residual = 0.770617, Final residual = 0.0112283, No Iterations 1 GAMG: Solving for p, Initial residual = 1, Final residual = 3.34459e+74, No Iterations 50 time step continuity errors : sum local = 2.15853e+83, global = 2.27242e+82, cumulative = 2.27242e+82 PIMPLE: iteration 2 smoothSolver: Solving for Ux, Initial residual = 0.998805, Final residual = 1.80506, No Iterations 1000 smoothSolver: Solving for Uy, Initial residual = 1, Final residual = 1.93583e-05, No Iterations 1 smoothSolver: Solving for Uz, Initial residual = 0.000531627, Final residual = 1.42642e-07, No Iterations 1 #0 Foam::error:rintStack(Foam::Ostream&) in "/home/alpha/OpenFOAM/OpenFOAM-2.1.x/platforms/linux64GccDPOpt/lib/libOpenFOAM.so" #1 Foam::sigFpe::sigHandler(int) in "/home/alpha/OpenFOAM/OpenFOAM-2.1.x/platforms/linux64GccDPOpt/lib/libOpenFOAM.so" #2 in "/lib/x86_64-linux-gnu/libc.so.6" #3 Foam:ICPreconditioner::calcReciprocalD(Foam::Fie ld&, Foam::lduMatrix const&) in "/home/alpha/OpenFOAM/OpenFOAM-2.1.x/platforms/linux64GccDPOpt/lib/libOpenFOAM.so" #4 Foam:ICSmoother:ICSmoother(Foam::word const&, Foam::lduMatrix const&, Foam::FieldField const&, Foam::FieldField const&, Foam::UPtrList const&) in "/home/alpha/OpenFOAM/OpenFOAM-2.1.x/platforms/linux64GccDPOpt/lib/libOpenFOAM.so" #5 Foam:ICGaussSeidelSmoother:ICGaussSeidelSmooth er(Foam::word const&, Foam::lduMatrix const&, Foam::FieldField const&, Foam::FieldField const&, Foam::UPtrList const&) in "/home/alpha/OpenFOAM/OpenFOAM-2.1.x/platforms/linux64GccDPOpt/lib/libOpenFOAM.so" #6 Foam::lduMatrix::smoother::addsymMatrixConstructor ToTable::New(Foam::w ord const&, Foam::lduMatrix const&, Foam::FieldField const&, Foam::FieldField const&, Foam::UPtrList const&) in "/home/alpha/OpenFOAM/OpenFOAM-2.1.x/platforms/linux64GccDPOpt/lib/libOpenFOAM.so" #7 Foam::lduMatrix::smoother::New(Foam::word const&, Foam::lduMatrix const&, Foam::FieldField const&, Foam::FieldField const&, Foam::UPtrList const&, Foam::dictionary const&) in "/home/alpha/OpenFOAM/OpenFOAM-2.1.x/platforms/linux64GccDPOpt/lib/libOpenFOAM.so" #8 Foam::GAMGSolver::initVcycle(Foam::PtrList >&, Foam::PtrList >&, Foam::PtrList&) const in "/home/alpha/OpenFOAM/OpenFOAM-2.1.x/platforms/linux64GccDPOpt/lib/libOpenFOAM.so" #9 Foam::GAMGSolver::solve(Foam::Field&, Foam::Field const&, unsigned char) const in "/home/alpha/OpenFOAM/OpenFOAM-2.1.x/platforms/linux64GccDPOpt/lib/libOpenFOAM.so" #10 Foam::fvMatrix::solve(Foam::dictionary const&) in "/home/alpha/OpenFOAM/OpenFOAM-2.1.x/platforms/linux64GccDPOpt/lib/libfiniteVolume.so" #11 in "/home/alpha/OpenFOAM/OpenFOAM-2.1.x/platforms/linux64GccDPOpt/bin/pimpleDyMFoam" #12 __libc_start_main in "/lib/x86_64-linux-gnu/libc.so.6" #13 in "/home/alpha/OpenFOAM/OpenFOAM-2.1.x/platforms/linux64GccDPOpt/bin/pimpleDyMFoam" Floating point exception ------------------------------------ If any one has a hint, please it welcome. I checked the boundary conditions but it doesn't seem to come from there for they are very similar to those of the propeller example. Thank all and best regards.

 April 17, 2012, 11:23 #6 Senior Member     Attesz Join Date: Mar 2009 Location: Munich Posts: 367 Rep Power: 10 Your k and omega is blowing up, i would have a look on them first. Try underrelaxation, especially for omega, and decrease the absolute tolerance to 1e-12 by setting the relTol to 0. Also have a look on the yplus and your wall modelling approach (if yplus is too small, forcing wallFunctions can cause blowing up the k and omega) __________________ I am doing CFD Consulting Services. Ich biete CFD Strömungssimulationen an.

 May 13, 2013, 09:02 #7 Member   Dogan Join Date: Nov 2012 Location: Bochum/Germany Posts: 42 Rep Power: 7 Hi all, i am working on a transient pump simulation, and i am getting a floating point exception. My geometry has a rotating part and a stationary part and between them, i have two cyclicGgi interfaces. I am using OF1.6 ext, and pimpleDyMFoam as the solver. My simulation starts to run, it runs until for a while, then it crashes with the floating point exception error message. I have tried almost everything, but i couldn't solve the problem. Now i am worried about that if i am doing something wrong about the mesh manipulating steps. or in general, can someone summarize me which steps do i have to follow before i start with the transient simulation? thanks in advance Dogan

 August 28, 2013, 23:27 #8 Member   Join Date: Mar 2009 Location: adelaide, SA, Australia Posts: 32 Rep Power: 10 Hi All, Sorry if the issue on this thread has been solved, but I've tried many things to get the pimpledymfoam run properly to my case: Flow Over A Square Cylinder with both ends are imposed with cyclic B.C. The Re is 22K and run with LES. Here is the chronology of my simulations, 1.0 Run with pisoFoam: Ok 2.0 Run with pimpleDymFoam: Not ok 2.1 Change cyclic to cyclicAMI: initially Ok, but blow up after fews time steps. 2.1.1 Change variables in the fvSolution: Ok 3.0 Increase the velocity from 1m/s to 2 m/s and run using the setting on 2.1.1: not ok, blow up after fews time steps. I'll appreciate if anyone can give me the advice on resolving this problem (It already took me 3months to find out the right solution) Thank YOU. __________________ mali

 December 6, 2013, 09:39 #9 Senior Member     Louis Gagnon Join Date: Mar 2009 Location: Milano, Italy Posts: 258 Rep Power: 11 I'm affraid I can't be of any help here but I too have issues running pimpleDyMFoam. I've tried turbulent and laminar flow, various BC, various numerical schemes, various solution algorithms, etc. It seems the only solution which could work, and yet I have not tested it for long enough, is to use an extremely small Courant number (such as 0.05-0.2). And such a small Courant number sort of makes the use of the PIMPLE algorithm useless...

 December 7, 2013, 08:57 #10 Member   Join Date: Mar 2009 Location: adelaide, SA, Australia Posts: 32 Rep Power: 10 Hi Louisgag, What dynamicFvMesh solver u use for your pimpleDyMFoam simulations? I used displacementLaplacian with no errors. But the results a bit different from experiment, especially for the upper branch. __________________ mali

 December 9, 2013, 08:12 #11 Senior Member     Louis Gagnon Join Date: Mar 2009 Location: Milano, Italy Posts: 258 Rep Power: 11 Hi mali, I use multiSolidBodyMotionFvMesh. Another strange thing I noticed is that when the simulation diverges, I can restart it from an earlier save and it will not diverge again until later. In this mode I end up with a simulation that never really diverges since it can always be restarted. As anyone experienced this behavior ?

 December 12, 2013, 12:32 #12 Senior Member   sivakumar selvaraju Join Date: Mar 2009 Location: Cape Town - South Africa Posts: 197 Rep Power: 10 Hi There, I want to use pimpleDyMFoam, I have a small question. I want use 1/8 th of my fan geometry with cyclic faces, is it possible can I use pimpleDyMFoam for this case? or do I need to use full 8 bladed geometry? Please clear my doubt. Thanks, Siva

 December 13, 2013, 04:32 #13 Senior Member   Onno Join Date: Jan 2012 Location: Germany Posts: 120 Rep Power: 9 Could maybe send of what you want to achieve? But I am afraid with the regular OpenFOAM it's not possible. Instead have a look at the extend-Version and overlapGGI.

 December 13, 2013, 04:43 #14 Senior Member   sivakumar selvaraju Join Date: Mar 2009 Location: Cape Town - South Africa Posts: 197 Rep Power: 10 Dear Onno, Thanks for your reply, so far I am using MRFSimpleFoam, the results are fine for high volume flow rate, but for low volume flow rate, I am not able to attain the convergence and its oscillating badly, so I decided to go for transient simulation with pimpleDyMFoam. My ultimate aim is to do low volume flow rate simulation. simulating full geometry is not a good option, because the mesh size will be really too much. suggest me something, Thanks, Siva

 December 13, 2013, 04:51 #15 Senior Member   Onno Join Date: Jan 2012 Location: Germany Posts: 120 Rep Power: 9 Like I said, please post a drawing of your geometry. I What is your goal? What type of mesh are you using? Which turbulence models, which solvers, which schemes?

December 13, 2013, 05:02
#16
Senior Member

sivakumar selvaraju
Join Date: Mar 2009
Location: Cape Town - South Africa
Posts: 197
Rep Power: 10

As I said in the previous post, aim is to simulate low volume flow rate.

What type of mesh are you using?

Fully hex mesh (non conformal)

Which turbulence models, which solvers, which schemes?

KEpsilon turbulence model, pimpleDyMFoam, mostly Upwind ( I am not concerning about the accuracy)

As you requested, I have attached the fig. please have a look.

Thanks,
Siva
Attached Files
 fig.pdf (22.3 KB, 47 views)

 December 13, 2013, 05:11 #17 Senior Member   Onno Join Date: Jan 2012 Location: Germany Posts: 120 Rep Power: 9 Could you maybe send your fvSchemes and fvSolution as well? What timeStep/maxCo are you using?

 December 13, 2013, 05:30 #18 Senior Member   sivakumar selvaraju Join Date: Mar 2009 Location: Cape Town - South Africa Posts: 197 Rep Power: 10 Hi, my question is bit away from our discussion, just I want to check, is it possible to do simulation with cyclic faces (1/8th of Geometry using pimpleDyMFoam). After getting clear idea, I will go forward with settings. right now I tried fvSchemes and fvSolutions from propeller case. I have edited the mxCo number thats it. I know I need to do more refinement according to my case, but I didnt do anything so far. Thanks, Siva

 December 13, 2013, 05:50 #19 Senior Member   Onno Join Date: Jan 2012 Location: Germany Posts: 120 Rep Power: 9 If the mesh motion causes the interfaces to stop matching, then AMI can't handle it, but overlapGGI can. See here: http://web.student.chalmers.se/group...SlidesOFW5.pdf

 December 13, 2013, 05:58 #20 Senior Member   sivakumar selvaraju Join Date: Mar 2009 Location: Cape Town - South Africa Posts: 197 Rep Power: 10 Thanks Onno, I will have a look. Siva

 Thread Tools Display Modes Linear Mode

 Posting Rules You may not post new threads You may not post replies You may not post attachments You may not edit your posts BB code is On Smilies are On [IMG] code is On HTML code is OffTrackbacks are On Pingbacks are On Refbacks are On Forum Rules

 Similar Threads Thread Thread Starter Forum Replies Last Post lostin4ever Main CFD Forum 0 November 11, 2009 05:26 tikulju OpenFOAM 0 October 19, 2009 05:37 shyam OpenFOAM Running, Solving & CFD 0 September 4, 2009 06:48 shiv Siemens 3 February 1, 2008 04:39 yonghong yan Main CFD Forum 4 July 27, 2002 02:06

All times are GMT -4. The time now is 08:47.