[MrSingh]

Hello experts,

I have been running a 3D simulation on a hemispherical blunt body of length 1 m with a spike attached in front also of 1 m in rhoCentralFoam.
The free-stream conditions are:
U = 2339.26 m/s / Mach 6.82
P = 101325 Pa
T = 300 K
mu = 0.011965
rho_inf = 1.176407
Re no. = 0.23 * 10^6
Other thermal properties like Cv are of standard air.
Both the top wall and the bottom wall is supersonicFreestream.
I am also using k-epsilon turbulence model.

It is a fine structured mesh with a good quality. But when I try to run the simulation, it crashes with the error:

Mean and max Courant Numbers = 0.00171279 0.543028
Time = 1e-08

diagonal:  Solving for rho, Initial residual = 0, Final residual = 0, No Iterations 0
diagonal:  Solving for rhoUx, Initial residual = 0, Final residual = 0, No Iterations 0
diagonal:  Solving for rhoUy, Initial residual = 0, Final residual = 0, No Iterations 0
diagonal:  Solving for rhoUz, Initial residual = 0, Final residual = 0, No Iterations 0
smoothSolver:  Solving for Ux, Initial residual = 0.999999, Final residual = 9.9914e-06, No Iterations 613
smoothSolver:  Solving for Uy, Initial residual = 1, Final residual = 9.90744e-06, No Iterations 114
smoothSolver:  Solving for Uz, Initial residual = 1, Final residual = 9.91186e-06, No Iterations 114
diagonal:  Solving for rhoE, Initial residual = 0, Final residual = 0, No Iterations 0
smoothSolver:  Solving for e, Initial residual = 6.68248e-05, Final residual = 9.6125e-06, No Iterations 1


--> FOAM FATAL ERROR: (openfoam-2212 patch=230110)
Negative initial temperature T0: -21.4718

    From Foam::scalar Foam::species::thermo<Thermo, Type>::T(Foam::scalar, Foam::scalar, Foam::scalar, Foam::scalar (Foam::species::thermo<Thermo, Type>::*)(Foam::scalar, Foam::scalar) const, Foam::scalar (Foam::species::thermo<Thermo, Type>::*)(Foam::scalar, Foam::scalar) const, Foam::scalar (Foam::species::thermo<Thermo, Type>::*)(Foam::scalar) const) const [with Thermo = Foam::hConstThermo<Foam::perfectGas<Foam::specie> >; Type = Foam::sensibleInternalEnergy; Foam::scalar = double; Foam::species::thermo<Thermo, Type> = Foam::species::thermo<Foam::hConstThermo<Foam::perfectGas<Foam::specie> >, Foam::sensibleInternalEnergy>]
    in file ./src/thermophysicalModels/specie/lnInclude/thermoI.H at line 57.

FOAM aborting

I tried changing the tolerances, scheme types, also added a fvOptions file with the code:

limitT
{
    type       limitTemperature;
    min        100;
    max        1000;
    selectionMode all;
}

but this also didn't work. It crashes on the first iteration. Also kept the deltaT quite low but that also didn't work. Please somebody tell me some solution for this.
fvSchemes:

fluxScheme          Kurganov;

ddtSchemes
{
    default         Euler;
}

gradSchemes
{
    default         Gauss linear;
}

divSchemes
{
    default         none;

    div(phi,U)      Gauss limitedLinearV 1;

    div(phi,e)      Gauss limitedLinear 1;
    div(phid,p)     Gauss limitedLinear 1;
    div(phi,K)      Gauss limitedLinear 1;
    div(phiv,p)     Gauss limitedLinear 1;
    div(tauMC)      Gauss linear;

    turbulence      Gauss upwind;
    div(phi,k)      $turbulence;
    div(phi,epsilon) $turbulence;

    div(((rho*nuEff)*dev2(T(grad(U))))) Gauss linear;
}

laplacianSchemes
{
    default         Gauss linear corrected;
}

interpolationSchemes
{
    default         linear;
    
    reconstruct(rho) vanLeer;
    reconstruct(U)  vanLeerV;
    reconstruct(T)  vanLeer;
}

snGradSchemes
{
    default         corrected;
}

fvSolution:

solvers
{
    "rho.*"
    {
        solver          diagonal;
    }

    "p.*"
    {
        solver          smoothSolver;
        smoother        symGaussSeidel;
        tolerance       1e-08;
        relTol          0;
    }

    "(U|e|R).*"
    {
        $p;
        tolerance       1e-05;
    }

    "(k|epsilon).*"
    {
        $p;
        tolerance       1e-08;
    }
}

PIMPLE
{
    nOuterCorrectors 2;
    nCorrectors      1;
    nNonOrthogonalCorrectors 0;
}

[dlahaye]

1/ First, test sanity of the case set-up by running using lower inlet mass flow rates.

2/ Second, try lower mass flow rates as initial guess for higher mass flow rate.

3/ Third, I imagine then negative temperatures can re-appear. Check whether using a limiter on temperature allows to run higher inflow rates. See https://www.openfoam.com/documentati...mitFields.html

4/ Fourth, get in touch in case difficulties persist.

[Alczem]

2/ Second, try lower mass flow rates as initial guess for higher mass flow rate.

I would also try to ramp up the velocity over a few seconds at the beginning of the run, instead of going full throttle instantly

[MrSingh]

Originally Posted by dlahaye

1/ First, test sanity of the case set-up by running using lower inlet mass flow rates.

2/ Second, try lower mass flow rates as initial guess for higher mass flow rate.

3/ Third, I imagine then negative temperatures can re-appear. Check whether using a limiter on temperature allows to run higher inflow rates. See https://www.openfoam.com/documentati...mitFields.html

4/ Fourth, get in touch in case difficulties persist.

Thank you for the suggestion.

[chc]

Hi, I'm working with the kOmegaSST model and am getting a similar issue. I've tried ramping the velocity but I still wind up with the same problem, have you been able to find a fix?