[okstatecheme]

I'm running a reactingFoam case with no reactions to track chemical species transport coming out the top of a vent stack with a crosswind.



Using the following thermophysical properties.


type hePsiThermo;
mixture reactingMixture;
transport sutherland;
thermo janaf;
energy sensibleEnthalpy;
equationOfState perfectGas;
specie specie;



I get about 1 second of run time (out of 20 seconds desired) before the simulation crashes. I get a temperature spike, the time step decreases to infinitesimally small increments, then the simulation crashes. Not sure what phenomena is going on here.



Here's the last log entry:

diagonal:  Solving for rho, Initial residual = 0, Final residual = 0, No Iterations 0
smoothSolver:  Solving for Ux, Initial residual = 1.63336e-16, Final residual = 1.63336e-16, No Iterations 0
smoothSolver:  Solving for Uy, Initial residual = 2.63377e-17, Final residual = 2.63377e-17, No Iterations 0
smoothSolver:  Solving for Uz, Initial residual = 2.56103e-17, Final residual = 2.56103e-17, No Iterations 0
smoothSolver:  Solving for O2, Initial residual = 6.29731e-14, Final residual = 6.29731e-14, No Iterations 0
smoothSolver:  Solving for H2O, Initial residual = 6.8088e-14, Final residual = 6.8088e-14, No Iterations 0
smoothSolver:  Solving for CO2, Initial residual = 2.01932e-20, Final residual = 2.01932e-20, No Iterations 0
smoothSolver:  Solving for H2S, Initial residual = 2.14111e-20, Final residual = 2.14111e-20, No Iterations 0
smoothSolver:  Solving for h, Initial residual = 3.94866e-16, Final residual = 3.94866e-16, No Iterations 0
min/max(T) = 237.675, 1102.75
DICPCG:  Solving for p, Initial residual = 2.40778e-15, Final residual = 2.40778e-15, No Iterations 0
diagonal:  Solving for rho, Initial residual = 0, Final residual = 0, No Iterations 0
time step continuity errors : sum local = 1.04371e-07, global = -4.49885e-09, cumulative = -4.31315e-05
DICPCG:  Solving for p, Initial residual = 2.40778e-15, Final residual = 2.40778e-15, No Iterations 0
diagonal:  Solving for rho, Initial residual = 0, Final residual = 0, No Iterations 0
time step continuity errors : sum local = 1.04371e-07, global = -4.49885e-09, cumulative = -4.3136e-05
DICPCG:  Solving for p, Initial residual = 2.40778e-15, Final residual = 2.40778e-15, No Iterations 0
diagonal:  Solving for rho, Initial residual = 0, Final residual = 0, No Iterations 0
time step continuity errors : sum local = 1.04371e-07, global = -4.49885e-09, cumulative = -4.31405e-05
smoothSolver:  Solving for omega, Initial residual = 2.97292e-19, Final residual = 2.97292e-19, No Iterations 0
smoothSolver:  Solving for k, Initial residual = 1.84934e-18, Final residual = 1.84934e-18, No Iterations 0
ExecutionTime = 7202.62 s  ClockTime = 7393 s

Courant Number mean: 1.20973e-10 max: 1.04921
deltaT = 6.04121e-29
--> FOAM Warning : 
    From function Time::operator++()
    in file db/Time/Time.C at line 1055
    Increased the timePrecision from 647 to 648 to distinguish between timeNames at time 1.1452
Time = 1.145202402849336831280879778205417096614837646484375

I'm guessing the fault has to do with my pressure/velocity boundary conditions?



p { margin-bottom: 0.1in; line-height: 120%; }
The ground (Bottom patch) is a wall, as is Stack, with a circular inletOutlet velocity patch (Sides). The Top is slip boundary condition. There is another inlet (Inlet) at the top of the stack where the chemicals are injected into the flow domain.


Here are the U & p bc's:



U

dimensions      [0 1 -1 0 0 0 0];

internalField   uniform (20 0 0);

boundaryField
{
    inlet
    {
        type            fixedValue;
        value           uniform (0 0 8.4);
    }
    bottom
    {
        type            fixedValue;
    value        uniform (0 0 0);
    }
    sides
    {
        type            inletOutlet;
    inletValue    uniform (20 0 0);
    value        uniform (20 0 0);
    }
    stack
    {
    type        fixedValue;
    value        uniform (0 0 0);
    }
    top
    {
        type            slip;
    }
}

p

dimensions      [1 -1 -2 0 0 0 0];

internalField   uniform 1e5;

boundaryField
{
    inlet
    {
        type            zeroGradient;
    }
    bottom
    {
        type            zeroGradient;
    }
    sides
    {
        type            totalPressure;
        U               U;
        phi             phi;
        rho             none;
        psi             none;
        gamma           1.4;
        p0              uniform 1e5;
    }
    stack
    {
    type        zeroGradient;
    }
    top
    {
        type            slip;
    }
}

Lastly the fvSolution dict:

solvers
{
    p
    {
        solver           PCG;
        preconditioner   DIC;
        tolerance        1e-7;
        relTol           0.01;
    }

    pFinal
    {
        $p;
        tolerance        1e-7;
        relTol           0.0;
    }

    "(rho|U|h|k|omega)"
    {
        solver          smoothSolver;
        smoother        symGaussSeidel;
        tolerance       1e-06;
        relTol          0.1;
    }

    "(rho|U|h|k|omega)Final"
    {
        $U;
    tolerance    1e-7;
        relTol          0;
    }

    Yi
    {
        $hFinal;
    }
}

PIMPLE
{
    momentumPredictor yes;
    nOuterCorrectors  1;
    nCorrectors     3;
    nNonOrthogonalCorrectors 0;
}

relaxationFactors
{
    fields
    {
        "p.*"           0.3;
        "rho.*"         1;
    }
    equations
    {
        "(U|h|k||omega).*" 0.7;
    }
}

Anybody see any issues with the BC?? Any insight as to what is causing the crash.