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-   -   Coupled equation problem (http://www.cfd-online.com/Forums/openfoam-solving/59179-coupled-equation-problem.html)

asteria February 4, 2008 05:03

Hi all~ I'm solving a transpo
 
Hi all~
I'm solving a transport equation. But here the problem is that transported variable and fluxes are coupled. or

phi=phi(psi)

ddt(psi) + div(phi,psi) = 0

Now I'm trying it explicitly using old time step psi to get phi. But the result is not good and it's stupid to solve such small time step. So I want to know if there is any way to solve this equation implicitly in OpenFOAM.

I'm sorry to double this thread.

Ah! and here phi is presented by phia and phib which are from twoPhaseEulerFoam solver and with some other constants. or,

forAll(m4, celli)
{
if(m4[celli]>1e-18)
D4vs[celli]=m6[celli]/m4[celli];
else
D4vs[celli]=0;
}
surfaceScalarField D4 = fvc::interpolate(D4vs);
surfaceScalarField phit4 = gw/18./nub*(rhoa-rhob)/rhob*D4;
surfaceScalarField phim4 = phib + phit4;

and here phim4 is the flux I'm using to get m4 field.
I expect that implicit solving will give more physical result and even help solving the problem in easier way.

any comments and advices are welcomed.

many pleasure with OpenFOAM.
with heart,

Hyunchang


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