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-   -   buoyantBoussinesqPisoFoam (http://www.cfd-online.com/Forums/openfoam-solving/130800-buoyantboussinesqpisofoam.html)

cristina March 4, 2014 12:36

buoyantBoussinesqPisoFoam
 
2 Attachment(s)
Hi all,

I have been working on a new solver by modifying the "buoyantBoussinesqPisoFoam".

I have added an explicit source to the temperature equation (as done in the tutorial "porousExplicitSourceReactingParcelFoam" and also an implict source to the momentum equation.
// Solve the momentum equation
fvVectorMatrix UEqn
(
fvm::ddt(U)
+ fvm::div(phi, U)
+ turbulence->divDevReff(U)
// - fvm::Sp(0.5*Cd*LAD*mag(U),U)
// -fvm::Sp(mag(fvc::Sp(Cd*LAD*0.5,U) ),U)
);
UEqn.relax();
if (momentumPredictor)
{
solve
(
UEqn
==
fvc::reconstruct
(
(
fvc::interpolate(rhok)*(g & mesh.Sf())
- fvc::snGrad(p)*mesh.magSf()
)
)
-fvc::Sp(mag(fvc::Sp(Cd*LAD*0.5,U) ),U)
);
}

where Cd is a constant and LAD is a scalarField. I set non uniform values by means of setFieldDict.



//solve the temperature equation
{
volScalarField kappaEff
(
"kappaEff",
turbulence->nu()/Pr + turbulence->nut()/Prt
);
fvScalarMatrix TEqn
(
fvm::ddt(T)
+ fvm::div(phi, T)
- fvm::laplacian(kappaEff, T)
==
temperatureSource.Su()
);
TEqn.relax();
TEqn.solve();
rhok = 1.0 - beta*(T - TRef);
}

The temperature source is set to a determined reion by means of cellset.

The solver compiles (see attached), but when I intend to run a case, the velocity increases really fast and the simulation crashes. I cannot find the error... ┐maybe in my boundary conditions? (see also case attached).

I would really appretiate any help!

Thanks in advance
Cristina

cristina March 5, 2014 04:43

Can anyone help me? This case is driving me crazy. I think it is a question of the pressure boundary conditions....


I attach the error:

Time = 1
Courant Number mean: 0 max: 0 velocity magnitude: 0
deltaT = 1.2
DILUPBiCG: Solving for Ux, Initial residual = 1, Final residual = 3.85069e-07, No Iterations 2
DILUPBiCG: Solving for Uy, Initial residual = 1, Final residual = 2.56645e-06, No Iterations 4
DILUPBiCG: Solving for Uz, Initial residual = 1, Final residual = 3.41222e-07, No Iterations 2
DILUPBiCG: Solving for T, Initial residual = 1, Final residual = 7.92614e-07, No Iterations 3
DICPCG: Solving for p, Initial residual = 1, Final residual = 0.0849405, No Iterations 58
time step continuity errors : sum local = 0.130643, global = -0.00370545, cumulative = -0.00370545
DICPCG: Solving for p, Initial residual = 0.416228, Final residual = 9.55017e-08, No Iterations 121
time step continuity errors : sum local = 1.74235e-06, global = 6.31575e-08, cumulative = -0.00370539
DILUPBiCG: Solving for epsilon, Initial residual = 0.946356, Final residual = 5.44074e-06, No Iterations 4
DILUPBiCG: Solving for k, Initial residual = 1, Final residual = 4.69753e-06, No Iterations 24
bounding k, min: 0 max: 1.26149 average: 0.731538
ExecutionTime = 0.87 s ClockTime = 0 s
Calculating averages
Time = 2.2
Courant Number mean: 3.273 max: 108.448 velocity magnitude: 25.3325
deltaT = 0.00553259
DILUPBiCG: Solving for Ux, Initial residual = 0.0131585, Final residual = 7.80769e-07, No Iterations 2
DILUPBiCG: Solving for Uy, Initial residual = 0.00882209, Final residual = 3.03072e-07, No Iterations 2
DILUPBiCG: Solving for Uz, Initial residual = 0.026238, Final residual = 3.4694e-08, No Iterations 3
DILUPBiCG: Solving for T, Initial residual = 0.0121135, Final residual = 1.79591e-07, No Iterations 2
DICPCG: Solving for p, Initial residual = 0.806607, Final residual = 0.0711915, No Iterations 9
time step continuity errors : sum local = 0.00013445, global = 5.87015e-06, cumulative = -0.00369952
DICPCG: Solving for p, Initial residual = 0.205045, Final residual = 9.95087e-08, No Iterations 127
time step continuity errors : sum local = 3.6426e-10, global = -1.26168e-11, cumulative = -0.00369952


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