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-   -   Hello Foamers..... (http://www.cfd-online.com/Forums/openfoam/90487-hello-foamers.html)

 Tushar@cfd July 12, 2011 01:15

Hello Foamers: need mhdFoam help

I am working on mhdFoam from past few weeks, my problem comes when I do change the transportProperties: since I want to check for the air as a conducting fluid so I am putting the Properties of Air values in it.. and studying the effect of variation on boundary layer when it flows over the flat plate... In my case velocity is quite small of 4 m/s...
when I run my case it runs for few iteration and then courant no. keeps on increasing after few iteration and even the variables U, P, B, and pB stop converging after some iteration..
The boundary condition in my case are:
1) velocity inlet and pressure outlet..
2) Far-field at the surrounding and no-slip at walls...
Even i tried with the other BC's:
1) pressure inlet and velocity outlet...
2) Far-field at the surrounding and no-slip at walls...

But the solution didn't converge after some iteration and shows the following errors:

#### solver stops after some run #######

Courant Number mean: 4.08481e+77 max: 3.35924e+82
DILUPBiCG: Solving for Ux, Initial residual = 1, Final residual = 505337, No Iterations 1001
DILUPBiCG: Solving for Uy, Initial residual = 1, Final residual = 1.1354e+07, No Iterations 1001
DILUPBiCG: Solving for Uz, Initial residual = 1, Final residual = 1.30113e+06, No Iterations 1001
DICPCG: Solving for p, Initial residual = 1, Final residual = 6.32227, No Iterations 1001
time step continuity errors : sum local = 1.50302e+103, global = -3.0307e+97, cumulative = -3.0307e+97
DICPCG: Solving for p, Initial residual = 0.999369, Final residual = 4.20609, No Iterations 1001
time step continuity errors : sum local = 2.56876e+109, global = 2.06169e+102, cumulative = 2.06166e+102
#0 Foam::error::printStack(Foam::Ostream&) in "/home/iitgn/OpenFOAM/OpenFOAM-1.6/lib/linuxGccDPOpt/libOpenFOAM.so"
#1 Foam::sigFpe::sigFpeHandler(int) in "/home/iitgn/OpenFOAM/OpenFOAM-1.6/lib/linuxGccDPOpt/libOpenFOAM.so"
#2 Uninterpreted:
#3 Foam::PCG::solve(Foam::Field<double>&, Foam::Field<double> const&, unsigned char) const in "/home/iitgn/OpenFOAM/OpenFOAM-1.6/lib/linuxGccDPOpt/libOpenFOAM.so"
#4 Foam::fvMatrix<double>::solve(Foam::dictionary const&) in "/home/iitgn/OpenFOAM/OpenFOAM-1.6/lib/linuxGccDPOpt/libfiniteVolume.so"
#5
in "/home/iitgn/OpenFOAM/OpenFOAM-1.6/applications/bin/linuxGccDPOpt/plasmairFoam"
#6 __libc_start_main in "/lib/tls/i686/cmov/libc.so.6"
#7
in "/home/iitgn/OpenFOAM/OpenFOAM-1.6/applications/bin/linuxGccDPOpt/plasmairFoam"
Floating point exception

I would like to know, Has anyone tried this case earlier?

 Bernhard July 12, 2011 02:01

Does your case converge without the MHD-part?

 Tushar@cfd July 12, 2011 02:59

Hi bernhard,

I got your point.. You are right the equations won't be sufficient for this case as it won't reach convergence.. I need to modify as per my problem case... Thank you..

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