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#21 |
Senior Member
Baris (Heewa)
Join Date: Jan 2013
Location: Japan
Posts: 130
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Dear Alexey,
What do you mean exactly by saying "we arrived to the point where you can describe the problem you are trying to simulate" and how did you understand that 0.1 MPa is to large. In my simulation, outside is environment. Therefore, i set it atmospheric pressure. Ok, i will try 0 for pressure and will set the relaxation factors according to your advises. I will let you know results. Thanks so much B. |
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#22 |
Senior Member
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Well,
I meant - "tell us about physical side of the problem you're trying to simulate", geometry, inflow/outflow conditions etc. Cause I have almost no knowledge about your problem, I can only guess what's going on and give general hints like "change relaxation factors, change PIMPLE dictionary" but the problem maybe elsewhere (for example in wrong direction of g). |
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#23 |
Senior Member
Baris (Heewa)
Join Date: Jan 2013
Location: Japan
Posts: 130
Rep Power: 13 ![]() |
Dear Alexey,
I have tried following different cases: 1. 0/ k-epsilon I have changed wallFucntion setting =>as ZeroGradient 2. U inlet ==> FixedValue outlet= intletOutlet and outlet { type pressureInletOutletVelocity; value uniform (0 0 0); inletValue uniform (0 0 0); 3. i have used relaxation factors: Code:
relaxationFactors { fields { } equations { "U.*" 0.7; "k.*" 0.5; => from 1 to 0.5 tried different values "epsilon.*" 0.5; => from 1 to 0.5 "p_rgh.*" 0.3; } } inlet ==> zeroGradient Outlet==> fixedValues ==>1e5, 1e4...0 (gradully decreased until 0) and also for outlet i tried: Code:
outlet { type fixedMeanValue; meanValue 0 and 1e5; value uniform 0 and 1e5; } All of these different challenges gives again following divergence error : ![]() ![]() ![]() ![]() Code:
ime step continuity errors : sum local = 981070, global = -2.61762e-10, cumulative = 0.00804153 PIMPLE: iteration 49 GAMG: Solving for p_rgh, Initial residual = 4.69143e-09, Final residual = 4.69143e-09, No Iterations 0 GAMG: Solving for p_rgh, Initial residual = 4.69143e-09, Final residual = 4.69143e-09, No Iterations 0 time step continuity errors : sum local = 1.44349e+06, global = -3.62086e-10, cumulative = 0.00804153 GAMG: Solving for p_rgh, Initial residual = 6.18678e-09, Final residual = 6.18678e-09, No Iterations 0 GAMG: Solving for p_rgh, Initial residual = 6.18678e-09, Final residual = 6.18678e-09, No Iterations 0 time step continuity errors : sum local = 1.90359e+06, global = -3.35302e-10, cumulative = 0.00804153 PIMPLE: iteration 50 GAMG: Solving for p_rgh, Initial residual = 9.10213e-09, Final residual = 9.10213e-09, No Iterations 0 GAMG: Solving for p_rgh, Initial residual = 9.10213e-09, Final residual = 9.10213e-09, No Iterations 0 time step continuity errors : sum local = 2.80061e+06, global = -4.94029e-10, cumulative = 0.00804153 GAMG: Solving for p_rgh, Initial residual = 1.20034e-08, Final residual = 9.50047e-10, No Iterations 1 GAMGPCG: Solving for p_rgh, Initial residual = 4.32284e-15, Final residual = 4.32284e-15, No Iterations 0 time step continuity errors : sum local = 994878, global = -2.11248e-10, cumulative = 0.00804153 PIMPLE: not converged within 50 iterations ExecutionTime = 1974.23 s ClockTime = 2002 s Courant Number mean: 6.58573e+06 max: 2.47105e+13 deltaT = 2.17834e-30 --> FOAM Warning : From function Time::operator++() in file db/Time/Time.C at line 1010 Increased the timePrecision from 8 to 9 to distinguish between timeNames at time 6.97175e-05 Time = 6.97175051e-05 [11] #0 Foam::error::printStack(Foam::Ostream&)[3] #0 Foam::error::printStack(Foam::Ostream&)[7] #0 Foam::error::printStack(Foam::Ostream&)[6] #0 Foam::error::printStack(Foam::Ostream&)[10] #0 Foam::error::printStack(Foam::Ostream&)[9] #0 Foam::error::printStack(Foam::Ostream&) in "/opt/openfoam211/platforms/linux64GccDPOpt/lib/libOpenFOAM.so" [3] #1 Foam::sigFpe::sigHandler(int)[2] #0 Foam::error::printStack(Foam::Ostream&) in "/opt/openfoam211/platforms/linux64GccDPOpt/lib/libOpenFOAM.so" [7] #1 Foam::sigFpe::sigHandler(int) in "/opt/openfoam211/platforms/linux64GccDPOpt/lib/libOpenFOAM.so" [11] #1 Foam::sigFpe::sigHandler(int)[4] #0 Foam::error::printStack(Foam::Ostream&)[5] #0 Foam::error::printStack(Foam::Ostream&) in "/opt/openfoam211/platforms/linux64GccDPOpt/lib/libOpenFOAM.so" [9] #1 Foam::sigFpe::sigHandler(int) in "/opt/openfoam211/platforms/linux64GccDPOpt/lib/libOpenFOAM.so" [10] #1 Foam::sigFpe::sigHandler(int) in "/opt/openfoam211/platforms/linux64GccDPOpt/lib/libOpenFOAM.so" [7] #2 in "/opt/openfoam211/platforms/linux64GccDPOpt/lib/libOpenFOAM.so" [2] #1 Foam::sigFpe::sigHandler(int) in "/opt/openfoam211/platforms/linux64GccDPOpt/lib/libOpenFOAM.so" [3] #2 [0] #0 Foam::error::printStack(Foam::Ostream&)[1] #0 Foam::error::printStack(Foam::Ostream&) in "/opt/openfoam211/platforms/linux64GccDPOpt/lib/libOpenFOAM.so" [4] #1 Foam::sigFpe::sigHandler(int) in "/opt/openfoam211/platforms/linux64GccDPOpt/lib/libOpenFOAM.so" [5] #1 Foam::sigFpe::sigHandler(int) in "/opt/openfoam211/platforms/linux64GccDPOpt/lib/libOpenFOAM.so" [9] #2 in "/opt/openfoam211/platforms/linux64GccDPOpt/lib/libOpenFOAM.so" [11] #2 in "/lib/libc.so.6" [3] #3 in "/opt/openfoam211/platforms/linux64GccDPOpt/lib/libOpenFOAM.so" [10] #2 [8] #0 Foam::error::printStack(Foam::Ostream&) in "/lib/libc.so.6" [7] #3 in "/opt/openfoam211/platforms/linux64GccDPOpt/lib/libOpenFOAM.so" [6] #1 Foam::sigFpe::sigHandler(int) in "/lib/libc.so.6" [11] #3 in "/opt/openfoam211/platforms/linux64GccDPOpt/lib/libOpenFOAM.so" [2] #2 in "/lib/libc.so.6" [9] #3 in "/opt/openfoam211/platforms/linux64GccDPOpt/lib/libO in "/opt/openfoam211/platforms/penFOAM.so" [0] #1 linux64GccDPOpt/lib/libOpenFOAM.so" Foam::sigFpe::sigHandler(int)[1] #1 Foam::sigFpe::sigHandler(int) in "/lib/libc.so.6" [10] #3 in "/opt/openfoam211/platforms/linux64GccDPOpt/lib/libOpenFOAM.so" [5] #2 in "/opt/openfoam211/platforms/linux64GccDPOpt/lib/libOpenFOAM.so" [4] #2 in "/opt/openfoam211/platforms/linux64GccDPOpt/lib/libOpenFOAM.so" [8] #1 Foam::sigFpe::sigHandler(int) in "/lib/libc.so.6" [2] #3 [7] in "/home/yusuke/OpenFOAM/yusuke-2.1.1/platforms/linux64GccDPOpt/bin/RNGinterPhaseChangeFoam" [7] #4 [3] in "/home/yusuke/OpenFOAM/yusuke-2.1.1/platforms/linux64GccDPOpt/bin/RNGinterPhaseChangeFoam" [3] #4 [11] in "/home/yusuke/OpenFOAM/yusuke-2.1.1/platforms/linux64GccDPOpt/bin/RNGinterPhaseChangeFoam" [11] #4 in "/lib/libc.so.6" [5] #3 in "/opt/openfoam211/platforms/linux64GccDPOpt/lib/libOpenFOAM.so" [6] #2 in "/opt/openfoam211/platforms/linux64GccDPOpt/lib/libOpenFOAM.so" [1] #2 in "/lib/ in "/opt/openfoam211/platforms/linux64GccDPOpt/lib/libOpenFOAM.so" [0] #2 libc.so.6" [4] #3 [10] in "/home/yusuke/OpenFOAM/yusuke-2.1.1/platforms/linux64GccDPOpt/bin/RNGinterPhaseChangeFoam" [10] #4 in "/lib/libc.so.6" [1] #3 in "/opt/openfoam211/platforms/linux64GccDPOpt/lib/libOpenFOAM.so" [8] #2 in "/lib/libc.so.6" [0] #3 [2] in "/home/yusuke/OpenFOAM/yusuke-2.1.1/platforms/linux64GccDPOpt/bin/RNGinterPhaseChangeFoam" [2] #4 [11] in "/home/yusuke/OpenFOAM/yusuke-2.1.1/platforms/linux64GccDPOpt/bin/RNGinterPhaseChangeFoam" [11] #5 [9] in "/home/yusuke/OpenFOAM/yusuke-2.1.1/platforms/linux64GccDPOpt/bin/RNGinterPhaseChangeFoam" [9] #4 in "/lib/libc.so.6" [6] #3 [3] in "/home/yusuke/OpenFOAM/yusuke-2.1.1/platforms/linux64GccDPOpt/bin/RNGinterPhaseChangeFoam" [3] #5 [4] in "/home/yusuke/OpenFOAM/yusuke-2.1.1/platforms/linux64GccDPOpt/bin/RNGinterPhaseChangeFoam" [4] #4 [7] in "/home/yusuke/OpenFOAM/yusuke-2.1.1/platforms/linux64GccDPOpt/bin/RNGinterPhaseChangeFoam" [7] #5 in "/lib/libc.so.6" [8] #3 [5] in "/home/yusuke/OpenFOAM/yusuke-2.1.1/platforms/linux64GccDPOpt/bin/RNGinterPhaseChangeFoam" [5] #4 [9] in "/home/yusuke/OpenFOAM/yusuke-2.1.1/platforms/linux64GccDPOpt/bin/RNGinterPhaseChangeFoam" [9] #5 [11] in "/home/yusuke/OpenFOAM/yusuke-2.1.1/platforms/linux64GccDPOpt/bin/RNGinterPhaseChangeFoam" [11] #6 __libc_start_main[0] in "/home/yusuke/OpenFOAM/yusuke-2.1.1/platforms/linux64GccDPOpt/bin/RNGinterPhaseChangeFoam" [0] #4 [1] in "/home/yusuke/OpenFOAM/yusuke-2.1[3] in "/home/yusuke/OpenFOAM/yusuke.1/platforms/linux64GccDPOpt/bin/RNGinterP-2.1.1/platforms/linux64GccDPOpt/bin/RhaseChangeFoam" NGinterPhaseChangeFoam" [1] #4 [3] #6 __libc_start_main [2] in "/home/yusuke/OpenFOAM/yusuke-2.1.1/platforms/linux64GccDPOpt/bin/RNGinterPhaseChangeFoam" [2] #5 [6] in "/home/yusuke/OpenFOAM/yusuke-2.1.1/platforms/linux64GccDPOpt/bin/RNGinterPhaseChangeFoam" [6] #4 [10] in "/home/yusuke/OpenFOAM/yusuke-2.1.1/platforms/linux64GccDPOpt/bin/RNGinterPhaseChangeFoam" [10] #5 in "/lib/libc.so.6" [11] #7 [7] in "/home/yusuke/OpenFOAM/yusuke-2.1.1/platforms/linux64GccDPOpt/bin/RNGinterPhaseChangeFoam" [7] #6 __libc_start_main in "/lib/libc.so.6" [3] #7 [4] in "/home/yusuke/OpenFOAM/yusuke-2.1.1/platforms/linux64GccDPOpt/bin/RNGinterPhaseChangeFoam" [4] #5 [9] in "/home/yusuke/OpenFOAM/yusuke-2.1.1/platforms/linux64GccDPOpt/bin/RNGinterPhaseChangeFoam" [9] #6 __libc_start_main[6] in "/home/yusuke/OpenFOAM/yusuke-2.1.1/platforms/linux64GccDPOpt/bin/RNGinterPhaseChangeFoam" [6] #5 in "/lib/libc.so.6" [7] #7 [1] in "/home/yusuke/OpenFOAM/yusuke-2.1.1/platforms/linux64GccDPOpt/bin/RNGinterPhaseChangeFoam" [1] #5 [2] in "/home/yusuke/OpenFOAM/yusuke-2.1.1/platforms/linux64GccDPOpt/bin/RNGinterPhaseChangeFoam" [2] #6 __libc_start_main [10] in "/home/yusuke/OpenFOAM/yusuke-2.1.1/platforms/linux64GccDPOpt/bin/RNGinterPhaseChangeFoam" [10] #6 __libc_start_main[5] in "/home/yusuke/OpenFOAM/yusuke-2.1.1/platforms/linux64GccDPOpt/bin/RNGinterPhaseChangeFoam" [5] #5 [8] in "/home/yusuke/OpenFOAM/yusuke-2.1.1/platforms/linux64GccDPOpt/bin/RNGinterPhaseChangeFoam" [8] #4 in "/lib/libc.so.6" [2] #7 [11] in "/home/yusuke/OpenFOAM/yusuke-2.1.1/platforms/linux64GccDPOpt/bin/RNGinterPhaseChangeFoam" [VENUS:26554] *** Process received signal *** [VENUS:26554] Signal: Floating point exception (8) [VENUS:26554] Signal code: (-6) [VENUS:26554] Failing at address: 0x3e8000067ba [VENUS:26554] [ 0] /lib/libc.so.6(+0x33af0) [0x7f17f47d3af0] [VENUS:26554] [ 1] /lib/libc.so.6(gsignal+0x35) [0x7f17f47d3a75] [VENUS:26554] [ 2] /lib/libc.so.6(+0x33af0) [0x7f17f47d3af0] [VENUS:26554] [ 3] RNGinterPhaseChangeFoam() [0x4a8442] [VENUS:26554] [ 4] RNGinterPhaseChangeFoam() [0x4b74fd] [VENUS:26554] [ 5] RNGinterPhaseChangeFoam() [0x435358] [VENUS:26554] [ 6] /lib/libc.so.6(__libc_start_main+0xfd) [0x7f17f47bec4d] [VENUS:26554] [ 7] RNGinterPhaseChangeFoam() [0x42b849] [VENUS:26554] *** End of error message *** in "/lib/libc.so.6" [10] #7 [0] in "/home/yusuke/OpenFOAM/yusuke-2.1.1/platforms/linux64GccDPOpt/bin/RNGinterPhaseChangeFoam" [0] #5 in "/lib/libc.so.6" [9] #7 [3] in "/home/yusuke/OpenFOAM/yusuke-2.1.1/platforms/linux64GccDPOpt/bin/RNGinterPhaseChangeFoam" [VENUS:26546] *** Process received signal *** [VENUS:26546] Signal: Floating point exception (8) [VENUS:26546] Signal code: (-6) [VENUS:26546] Failing at address: 0x3e8000067b2 [VENUS:26546] [ 0] /lib/libc.so.6(+0x33af0) [0x7ff896532af0] [VENUS:26546] [ 1] /lib/libc.so.6(gsignal+0x35) [0x7ff896532a75] [VENUS:26546] [ 2] /lib/libc.so.6(+0x33af0) [0x7ff896532af0] [VENUS:26546] [ 3] RNGinterPhaseChangeFoam() [0x4a8483] [VENUS:26546] [ 4] RNGinterPhaseChangeFoam() [0x4b74fd] [VENUS:26546] [ 5] RNGinterPhaseChangeFoam() [0x435358] [VENUS:26546] [ 6] /lib/libc.so.6(__libc_start_main+0xfd) [0x7ff89651dc4d] [VENUS:26546] [ 7] RNGinterPhaseChangeFoam() [0x42b849] [VENUS:26546] *** End of error message *** [1] in "/home/yusuke/OpenFOAM/yusuke-2.1.1/platforms/linux64GccDPOpt/bin/RNGinterPhaseChangeFoam" [1] #6 __libc_start_main Thanks in advance. B |
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#24 |
Senior Member
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Hi,
well, as you don't want to share an exact description of the physical problem you are trying to simulate, let's continue guessing. 1. You run modified version of interPhaseChangeFoam, have you tried running original solver? Just to try to localize what's causing troubles with convergence. 2. The only modification you've made was that scaling factor for nut? Or you've done something else? Can you share your modified code? I can continue with questions using just the pictures and solver output you've posted but think it won't be very productive. |
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#25 |
Senior Member
Baris (Heewa)
Join Date: Jan 2013
Location: Japan
Posts: 130
Rep Power: 13 ![]() |
Dear Alexey,
Thanks so much for your reply. I think that you misunderstood. Of course i can share exact description of the physical problem. I am trying to simulate cavitation inside of nozzle. My nozzle shape is as you can see at thread #13. 1. yeah i have tried with original interphasechangefoam. I had one thread before you can see here: http://www.cfd-online.com/Forums/ope...foam_help.html In original case, cavitation took place inside of nozzle, extended until some level and then disappeared. That was the problem. After that in some papers i saw that RANS turbulence viscosity is calculated high and need to have some modification to decrease the nut Now what i am trying to do. 2. Yes i have only modification which is bold in the file of U.Eqn as follow: Code:
dimensionedScalar rhoUnit("rhoUnit", dimDensity, 1.0); surfaceScalarField muEff ( "muEff", twoPhaseProperties->muf() + fvc::interpolate((Foam::pow((0.017-rho/rhoUnit),5)/Foam::pow((0.017-998),5)*(998-0.017)+ 0.017)*rho*turbulence->nut()) ); fvVectorMatrix UEqn ( fvm::ddt(rho, U) + fvm::div(rhoPhi, U) - fvm::Sp(fvc::ddt(rho) + fvc::div(rhoPhi), U) - fvm::laplacian(muEff, U) - (fvc::grad(U) & fvc::grad(muEff)) //- fvc::div(muEff*(fvc::interpolate(dev2(fvc::grad(U))) & mesh.Sf())) ); UEqn.relax(); if (pimple.momentumPredictor()) { solve ( UEqn == fvc::reconstruct ( ( fvc::interpolate(interface.sigmaK())*fvc::snGrad(alpha1) - ghf*fvc::snGrad(rho) - fvc::snGrad(p_rgh) ) * mesh.magSf() ) ); } Please let me know what kind of info you want. Thanks B. |
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#26 |
Senior Member
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Well, cause modeling of cavitation is not something that I do, my thoughts will be quite general (i.e. maybe completely useless
![]() 1. When you were doing simulations with original interPhaseChangeFoam, what was in your PIMPLE dictionary? Are you sure that the solution converged on every time step? 2. If you need lower turbulent viscosity why not start with just modifying Cmu (if you're using k-epsilon model). Set it 100 time lower (9e-4) and see what will happen. 3. Finally are you sure that settings for cavitation model are correct? In general you've got several points of possible errors: ICs/BCs, cavitation model settings, transport model settings, your modification of the code. See the influence of these things on the results, locate the source of the problem (well, I guess it'll be code modification as without it code was at least running and simulation wasn't blowing up). Plot muEff with your modification, compare it to the values without modifications. See if it even make any sense. |
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