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-   -   rhosimplefoam running problem (http://www.cfd-online.com/Forums/openfoam-solving/75539-rhosimplefoam-running-problem.html)

aneshe April 28, 2010 09:26

rhosimplefoam running problem
 
Dear all,

I am newer to openfoam. I am running a case using rhosimplefoam. But after several iterations, errors happens.
Could you please tell me what's this error means?
It looks there are convergence problem.

Thanks in advance for you kindly help.

Best regards,
Aneshe.



Time = 6

DILUPBiCG: Solving for Ux, Initial residual = 0.462608, Final residual = 0.0410476, No Iterations 1
DILUPBiCG: Solving for Uy, Initial residual = 0.250651, Final residual = 0.0235479, No Iterations 1
DILUPBiCG: Solving for Uz, Initial residual = 0.3213, Final residual = 0.00371833, No Iterations 2
DILUPBiCG: Solving for h, Initial residual = 0.0610008, Final residual = 0.00256268, No Iterations 1
GAMG: Solving for p, Initial residual = 0.589161, Final residual = 0.0204743, No Iterations 8
time step continuity errors : sum local = 57.8693, global = -14.8249, cumulative = 10.8505
rho max/min : 159.76 0.441376
smoothSolver: Solving for epsilon, Initial residual = 0.999931, Final residual = 0.00372962, No Iterations 2
smoothSolver: Solving for k, Initial residual = 0.711263, Final residual = 7.32219e-09, No Iterations 2
ExecutionTime = 16.84 s ClockTime = 18 s

Time = 7

DILUPBiCG: Solving for Ux, Initial residual = 0.218558, Final residual = 0.00917327, No Iterations 1
DILUPBiCG: Solving for Uy, Initial residual = 0.234351, Final residual = 0.0103172, No Iterations 1
DILUPBiCG: Solving for Uz, Initial residual = 0.265696, Final residual = 0.0169588, No Iterations 1
DILUPBiCG: Solving for h, Initial residual = 0.187826, Final residual = 0.00812604, No Iterations 1
#0 Foam::error::printStack(Foam::Ostream&) in "/home/xshan/OpenFOAM/OpenFOAM-1.6/lib/linuxGccDPOpt/libOpenFOAM.so"
#1 Foam::sigFpe::sigFpeHandler(int) in "/home/xshan/OpenFOAM/OpenFOAM-1.6/lib/linuxGccDPOpt/libOpenFOAM.so"
#2 Uninterpreted:
#3 Foam::hPsiThermo<Foam::pureMixture<Foam::sutherlan dTransport<Foam::specieThermo<Foam::hConstThermo<F oam::perfectGas> > > > >::calculate() in "/home/xshan/OpenFOAM/OpenFOAM-1.6/lib/linuxGccDPOpt/libbasicThermophysicalModels.so"
#4 Foam::hPsiThermo<Foam::pureMixture<Foam::sutherlan dTransport<Foam::specieThermo<Foam::hConstThermo<F oam::perfectGas> > > > >::correct() in "/home/xshan/OpenFOAM/OpenFOAM-1.6/lib/linuxGccDPOpt/libbasicThermophysicalModels.so"
#5 main in "/home/xshan/OpenFOAM/OpenFOAM-1.6/applications/bin/linuxGccDPOpt/rhoSimpleFoam"
#6 __libc_start_main in "/lib/tls/i686/cmov/libc.so.6"
#7 _start at /usr/src/packages/BUILD/glibc-2.9/csu/../sysdeps/i386/elf/start.S:122
Floating point exception

truong_nm April 29, 2010 11:06

Can you describe your case ? :)
Seems that your density explodes after a few iterations :confused:

Sofia May 21, 2010 09:47

convergence trouble
 
Hi dear openfoamer,

I am new on openFoam and i am striving to make a subsonic flow around an airfoil work out with rhosimplefoam for the steady state case and hopefully later with rhoPisofoam for the transcient situation.

Having said that, I have exactly the same error as aneshe when using rhosimpleFoam. The running diverges after a couple of iterations. ( around 10 iteration :( )

I am at M = 0.5 using kepsilon turbulence model with the following features :

k = 1e-6 at both the inlet and the airfoil, the airfoil has the wall function = compressible::kqRWallFunction; and I assigned zerogradients elsewhere.

epsilon = 10 at both the inlet and the airfoil, the airfoil has the wall function = compressible::epsilonWallFunction with Cmu = 0.09; kappa = 0.41; E = 9.8;; and again i assigned zerogradient elsewhere.

I am a bit confused with mut and alphat files becauses i have no idea of the values and BC, I may assign.

I am quiet sure that the error comes from the BC choice because the mesh is ok.

Could someone please help me by recommanding for exemple BCs for my case.

Thanks in advance.

King Regards

Sofia

truong_nm May 21, 2010 09:53

I have always failed in running rhoSimpleFoam. An alternative solution is to combine a local time step and a transient solver (SLTS + rhoPisoFoam for example).

Sofia May 21, 2010 11:33

thank you a lot for the reply.

I have read on another thread that (SLTS + rhoPisoFoam) is almost equivalent to rhoPimpleFoam.

do you think rhopimplefoam is appropriate ? if it is the case could you give me some recommandation to run the case properly.

Best Regards,

Sofia


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