[Dan1788]

Hello all,

I am using reactingFOAM for an LES of premixed flame calculation (methane+air premixture) in OF-2.2.x. To ignite the flame, I set a patch of temperature using setFields like this: (I also set mass fraction of CO2 and H2O in this patch)



When I ran the simulation for a couple of time steps, the temperature field became something like this:



Ultimately however, the temperature in some cells went past 3500 K and the code produced NAN

Could someone tell me how to use the setFields utility correctly for a premixed flame ? Which zone should we patch with a temperature field ? Please help

[Dan1788]

Anyone who might know how to use setFields for flame ignition ??

[hajott]

reactingFoam crashes with NaNs when the temperature exceeds the maximum temperature which thermodynamic data are available for.

I don't think the problem is your setFieldsDict, but you would have to attach your case directory if you want feedback on your approach.

[Dan1788]

Hi Hajott,

Thanks for your reply. Basically a schematic of my flow domain looks like this:



My fvSchemes are the following:

ddtSchemes
{
    default         backward;
}

gradSchemes
{
    default         Gauss linear;
    grad(pd)        Gauss linear;
}

divSchemes
{
    default         none;

    div(phi,U)      Gauss limitedLinearV 1;
    div(phi,h)      Gauss limitedLinear 1;
    div(phi,Yi_h)   Gauss limitedLinear 1;
    div(phi,K)      Gauss limitedLinear 1;
    div(phid,pd)    Gauss limitedLinear 1;
    div(phi,epsilon) Gauss limitedLinear 1;
    div(phi,k)      Gauss limitedLinear 1;
    div((muEff*dev2(T(grad(U))))) Gauss linear;
}

laplacianSchemes
{
    //default         Gauss linear orthogonal;
    default         Gauss linear corrected;
}

interpolationSchemes
{
    default         linear;
}

snGradSchemes
{
   //default         orthogonal;
   default          corrected;
}

fluxRequired
{
    default         no;
    pd;
}

The fvSolution file is as follows:

solvers
{
    rho
    {
        solver           PCG;
        preconditioner   DIC;
        tolerance        1e-06;
        relTol           0.1;
    }

    rhoFinal
    {
        $rho;
        tolerance        1e-06;
        relTol           0;
    }

    pd
    {
        solver           GAMG;
        tolerance        1e-6;
        relTol           0.1;

	    maxIter		     100;	

        smoother         DICGaussSeidel;
	
        nPreSweeps       0;
        nPostSweeps      1;
	    nFinestSweeps    2;

        cacheAgglomeration true;

        nCellsInCoarsestLevel 50;
        agglomerator     faceAreaPair;
        mergeLevels      1;
    };

    pdFinal
    {
        solver           GAMG;
        tolerance        1e-6;
        relTol           1.0e-2;

	    maxIter		     100;	

        smoother         DICGaussSeidel;

        nPreSweeps       0;
        nPostSweeps      1;
	    nFinestSweeps    2;

        cacheAgglomeration true;

        nCellsInCoarsestLevel 50;
        agglomerator     faceAreaPair;
        mergeLevels      1;
    };

    "(U|h|k|epsilon)"
    {
        solver          PBiCG;
        preconditioner  DILU;
        tolerance       1e-06;
        relTol          0.1;
    }

    "(U|h|k|epsilon)Final"
    {
        solver          PBiCG;
        preconditioner  DILU;
        tolerance       1e-06;
        relTol          0;
    }

    Yi
    {
        $hFinal;
    }
}

PIMPLE
{
    momentumPredictor   yes;
    nOuterCorrectors    2;
    nCorrectors         3;
    nNonOrthogonalCorrectors 0;
}

For the boundary conditions, I use fixedValue for atmospheric pressure at outlet, inletOutlet for velocity and scalars at outlet, and slip wall boundary at the sides of my domain.

I have also attached my case in the zip file. Any comments or suggestions would be really appreciated