[randolph]

Hi everyone,

I have experienced some weird convergence issue with the transportFoam on a hpc. The simulation converges in 2 iterations...

Time = 1
DILUPBiCGStab:  Solving for T, Initial residual = 1, Final residual = 4.5508e-09, No Iterations 6
DILUPBiCGStab:  Solving for T, Initial residual = 1.48813e-238, Final residual = 2.17278e-239, No Iterations 1
DILUPBiCGStab:  Solving for T, Initial residual = 7.32543e-239, Final residual = 1.02164e-239, No Iterations 1

Time = 2
DILUPBiCGStab:  Solving for T, Initial residual = 4.76531e-239, Final residual = 6.39731e-240, No Iterations 1
DILUPBiCGStab:  Solving for T, Initial residual = 3.49174e-239, Final residual = 4.59086e-240, No Iterations 1
DILUPBiCGStab:  Solving for T, Initial residual = 2.73492e-239, Final residual = 3.54658e-240, No Iterations 1

SIMPLE solution converged in 2 iterations

End

Finalising parallel run

But If I start another exact same run, the model will behave well.

Time = 1

DILUPBiCGStab:  Solving for T, Initial residual = 1, Final residual = 4.54546e-09, No Iterations 6
DILUPBiCGStab:  Solving for T, Initial residual = 0.102393, Final residual = 2.91777e-09, No Iterations 5
DILUPBiCGStab:  Solving for T, Initial residual = 0.0527999, Final residual = 7.78017e-09, No Iterations 5

Time = 2

DILUPBiCGStab:  Solving for T, Initial residual = 0.0350811, Final residual = 4.8293e-09, No Iterations 5
DILUPBiCGStab:  Solving for T, Initial residual = 0.0260212, Final residual = 7.77216e-09, No Iterations 4
DILUPBiCGStab:  Solving for T, Initial residual = 0.0205409, Final residual = 5.81297e-09, No Iterations 4

..............

Has anyone experienced a similar issue? And what would be the cause? The following is my fvSolution file. I run the model with steadyState mode.

 
solvers
{
    T
    {
        solver          PBiCGStab;
        preconditioner  DILU;
        tolerance       1e-08;
        relTol          0;
		minIter         1;
    }
}

SIMPLE
{
    nNonOrthogonalCorrectors 0;
	consistent      yes;

    residualControl
    {
        T               1e-8;
    }

}

relaxationFactors
{
    equations
    {
        T               0.5;
    }
}

Any guidance will be appreciated.
Rdf