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March 31, 2010, 12:51 
pimpleDyMFoam diverging

#1 
Member
Join Date: May 2009
Posts: 51
Rep Power: 9 
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 = 3.73109e10 Time = 0.00065686 Pressure force = (5.77062e+11 1.75305e+13 1.484e05) Viscous force = (1.06804e+10 3.28055e+09 4.6907e05) Total force = (5.66381e+11 1.75338e+13 6.1747e05) Pressure force = (5.77062e+11 1.75305e+13 1.484e05) Viscous force = (1.06804e+10 3.28055e+09 4.6907e05) Total force = (5.66381e+11 1.75338e+13 6.1747e05) new force= (5.66381e+11 1.75338e+13 6.1747e05) 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 = 6.46833e07, No Iterations 1 DILUPBiCG: Solving for Uy, Initial residual = 0.000226988, Final residual = 1.6964e07, No Iterations 1 DICPCG: Solving for p, Initial residual = 0.936208, Final residual = 9.29128e07, No Iterations 303 time step continuity errors : sum local = 2.91692e12, global = 3.30302e14, cumulative = 2.10666e12 DILUPBiCG: Solving for Ux, Initial residual = 0.0011032, Final residual = 2.14598e08, No Iterations 1 DILUPBiCG: Solving for Uy, Initial residual = 0.00026622, Final residual = 5.22804e09, No Iterations 1 DICPCG: Solving for p, Initial residual = 0.474501, Final residual = 9.38896e07, No Iterations 298 time step continuity errors : sum local = 4.10823e12, global = 4.30266e14, cumulative = 2.14969e12 DILUPBiCG: Solving for nuTilda, Initial residual = 2.76369e06, Final residual = 2.76369e06, No Iterations 0 ExecutionTime = 24.02 s ClockTime = 24 s Courant Number mean: 0.0012636 max: 0.200559 deltaT = 4.47731e10 Time = 0.00065686 Pressure force = (3.14683e+13 2.90887e+14 0.000464347) Viscous force = (6.73597e+09 3.07824e+09 4.73848e06) 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 4.73848e06) 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 = 8.38248e08, No Iterations 2 DILUPBiCG: Solving for Uy, Initial residual = 0.0037189, Final residual = 6.18129e07, No Iterations 1 DICPCG: Solving for p, Initial residual = 0.614507, Final residual = 8.80742e07, No Iterations 344 time step continuity errors : sum local = 2.19871e12, global = 1.48693e14, cumulative = 2.16456e12 DILUPBiCG: Solving for Ux, Initial residual = 0.0376498, Final residual = 4.48819e09, No Iterations 2 DILUPBiCG: Solving for Uy, Initial residual = 0.00476686, Final residual = 1.9605e06, No Iterations 1 DICPCG: Solving for p, Initial residual = 0.494856, Final residual = 9.71665e07, No Iterations 320 time step continuity errors : sum local = 8.84475e12, global = 5.15065e14, cumulative = 2.21606e12 DILUPBiCG: Solving for nuTilda, Initial residual = 1.94363e05, Final residual = 1.35167e08, No Iterations 1 bounding nuTilda, min: 1.48587e17 max: 3.92394 average: 0.00253206 ExecutionTime = 26.15 s ClockTime = 26 s Courant Number mean: 0.00577774 max: 0.207404 deltaT = 5.37277e10 Time = 0.000656861 Pressure force = (2.07155e+09 5.18228e+15 0.0122243) Viscous force = (2.52242e+09 1.35877e+11 5.65746e05) 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 5.65746e05) 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 = 3.86788e06, No Iterations 3 DILUPBiCG: Solving for Uy, Initial residual = 0.139973, Final residual = 2.91468e06, No Iterations 3 DICPCG: Solving for p, Initial residual = 0.98152, Final residual = 9.09526e07, No Iterations 333 time step continuity errors : sum local = 2.52805e11, global = 4.02247e14, cumulative = 2.25629e12 DILUPBiCG: Solving for Ux, Initial residual = 0.40134, Final residual = 6.16425e06, No Iterations 4 DILUPBiCG: Solving for Uy, Initial residual = 0.0181964, Final residual = 2.29782e06, No Iterations 3 DICPCG: Solving for p, Initial residual = 0.981988, Final residual = 8.49443e07, No Iterations 293 time step continuity errors : sum local = 1.21941e09, global = 2.49295e12, cumulative = 4.74924e12 DILUPBiCG: Solving for nuTilda, Initial residual = 0.000310185, Final residual = 9.04832e06, 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/OpenFOAM1.6.x/lib/linuxGccDPOpt/libOpenFOAM.so" #1 Foam::sigFpe::sigFpeHandler(int) in "/home/greg/OpenFOAM/OpenFOAM1.6.x/lib/linuxGccDPOpt/libOpenFOAM.so" #2 Uninterpreted: #3 Foam::Time::adjustDeltaT() in "/home/greg/OpenFOAM/OpenFOAM1.6.x/lib/linuxGccDPOpt/libOpenFOAM.so" #4 Foam::Time::setDeltaT(double) in "/home/greg/OpenFOAM/OpenFOAM1.6.x/lib/linuxGccDPOpt/libOpenFOAM.so" #5 main in "/home/greg/OpenFOAM/OpenFOAM1.6.x/applications/bin/linuxGccDPOpt/pimpleDyMFoam" #6 __libc_start_main in "/lib/tls/i686/cmov/libc.so.6" #7 _start at /build/buildd/eglibc2.10.1/csu/../sysdeps/i386/elf/start.S:122 Floating point exception 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((1A(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: 7 
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: 7 
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: 51
Rep Power: 9 
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: 7 
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 = 1e05 Time = 7e05 solidBodyMotionFunctions::rotatingMotion::transfor mation(): Time = 7e05 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 = 1.09112e05, cumulative = 4.39653e05 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 = 7.2394e07, No Iterations 26 GAMG: Solving for p, Initial residual = 0.940662, Final residual = 9.79822e07, No Iterations 23 time step continuity errors : sum local = 5.83896e06, global = 5.30525e07, 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 = 1.42853e05, Final residual = 6.87541e07, 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 = 2.26963e09 Time = 7.00023e05 solidBodyMotionFunctions::rotatingMotion::transfor mation(): Time = 7.00023e05 transformation: ((0 0 8.67362e19) (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 = 6.31039e05, No Iterations 1 GAMG: Solving for p, Initial residual = 0.595319, Final residual = 9.86458e05, 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 = 5.86893e07, No Iterations 28 DILUPBiCG: Solving for Uy, Initial residual = 0.999998, Final residual = 7.80082e07, No Iterations 20 DILUPBiCG: Solving for Uz, Initial residual = 0.000201204, Final residual = 9.98882e07, No Iterations 5 GAMG: Solving for p, Initial residual = 0.879029, Final residual = 7.05858e07, 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 = 6.79817e07, 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 = 1.40989e37 > 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 7.00023e05 Time = 7.000227e05 solidBodyMotionFunctions::rotatingMotion::transfor mation(): Time = 7.00023e05 transformation: ((0 0 8.67362e19) (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 = 1.93583e05, No Iterations 1 smoothSolver: Solving for Uz, Initial residual = 0.000531627, Final residual = 1.42642e07, No Iterations 1 #0 Foam::error:rintStack(Foam::Ostream&) in "/home/alpha/OpenFOAM/OpenFOAM2.1.x/platforms/linux64GccDPOpt/lib/libOpenFOAM.so" #1 Foam::sigFpe::sigHandler(int) in "/home/alpha/OpenFOAM/OpenFOAM2.1.x/platforms/linux64GccDPOpt/lib/libOpenFOAM.so" #2 in "/lib/x86_64linuxgnu/libc.so.6" #3 Foam:ICPreconditioner::calcReciprocalD(Foam::Fie ld<double>&, Foam::lduMatrix const&) in "/home/alpha/OpenFOAM/OpenFOAM2.1.x/platforms/linux64GccDPOpt/lib/libOpenFOAM.so" #4 Foam:ICSmoother:ICSmoother(Foam::word const&, Foam::lduMatrix const&, Foam::FieldField<Foam::Field, double> const&, Foam::FieldField<Foam::Field, double> const&, Foam::UPtrList<Foam::lduInterfaceField const> const&) in "/home/alpha/OpenFOAM/OpenFOAM2.1.x/platforms/linux64GccDPOpt/lib/libOpenFOAM.so" #5 Foam:ICGaussSeidelSmoother:ICGaussSeidelSmooth er(Foam::word const&, Foam::lduMatrix const&, Foam::FieldField<Foam::Field, double> const&, Foam::FieldField<Foam::Field, double> const&, Foam::UPtrList<Foam::lduInterfaceField const> const&) in "/home/alpha/OpenFOAM/OpenFOAM2.1.x/platforms/linux64GccDPOpt/lib/libOpenFOAM.so" #6 Foam::lduMatrix::smoother::addsymMatrixConstructor ToTable<Foam:ICGaussSeidelSmoother>::New(Foam::w ord const&, Foam::lduMatrix const&, Foam::FieldField<Foam::Field, double> const&, Foam::FieldField<Foam::Field, double> const&, Foam::UPtrList<Foam::lduInterfaceField const> const&) in "/home/alpha/OpenFOAM/OpenFOAM2.1.x/platforms/linux64GccDPOpt/lib/libOpenFOAM.so" #7 Foam::lduMatrix::smoother::New(Foam::word const&, Foam::lduMatrix const&, Foam::FieldField<Foam::Field, double> const&, Foam::FieldField<Foam::Field, double> const&, Foam::UPtrList<Foam::lduInterfaceField const> const&, Foam::dictionary const&) in "/home/alpha/OpenFOAM/OpenFOAM2.1.x/platforms/linux64GccDPOpt/lib/libOpenFOAM.so" #8 Foam::GAMGSolver::initVcycle(Foam::PtrList<Foam::F ield<double> >&, Foam::PtrList<Foam::Field<double> >&, Foam::PtrList<Foam::lduMatrix::smoother>&) const in "/home/alpha/OpenFOAM/OpenFOAM2.1.x/platforms/linux64GccDPOpt/lib/libOpenFOAM.so" #9 Foam::GAMGSolver::solve(Foam::Field<double>&, Foam::Field<double> const&, unsigned char) const in "/home/alpha/OpenFOAM/OpenFOAM2.1.x/platforms/linux64GccDPOpt/lib/libOpenFOAM.so" #10 Foam::fvMatrix<double>::solve(Foam::dictionary const&) in "/home/alpha/OpenFOAM/OpenFOAM2.1.x/platforms/linux64GccDPOpt/lib/libfiniteVolume.so" #11 in "/home/alpha/OpenFOAM/OpenFOAM2.1.x/platforms/linux64GccDPOpt/bin/pimpleDyMFoam" #12 __libc_start_main in "/lib/x86_64linuxgnu/libc.so.6" #13 in "/home/alpha/OpenFOAM/OpenFOAM2.1.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: 357
Rep Power: 9 
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 1e12 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)
__________________
https://cfdfreelancing.com 

May 13, 2013, 09:02 

#7 
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Dogan
Join Date: Nov 2012
Location: Bochum/Germany
Posts: 42
Rep Power: 6 
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 
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Join Date: Mar 2009
Location: adelaide, SA, Australia
Posts: 32
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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

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 0.050.2). And such a small Courant number sort of makes the use of the PIMPLE algorithm useless...


December 7, 2013, 08:57 

#10 
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Join Date: Mar 2009
Location: adelaide, SA, Australia
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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

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

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 
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Onno
Join Date: Jan 2012
Location: Germany
Posts: 93
Rep Power: 8 
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 extendVersion and overlapGGI. 

December 13, 2013, 04:43 

#14 
Senior Member

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 
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Onno
Join Date: Jan 2012
Location: Germany
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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

Hi, here is some answer for your questions
What is your goal? 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 

December 13, 2013, 05:11 

#17 
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Onno
Join Date: Jan 2012
Location: Germany
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Could you maybe send your fvSchemes and fvSolution as well? What timeStep/maxCo are you using?


December 13, 2013, 05:30 

#18 
Senior Member

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 
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Onno
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Location: Germany
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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

Thanks Onno, I will have a look.
Siva 

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