[Alvro237]

Hello Everyone,

I am trying to simulate a rectangular rocket nozzle and the subsequent discharge to the atmosphere (1atm). I am using K-omega SST turbulence model to run a transient simulation. I am simulating 1/4 of the geometry, with one symmetry at the bottom and at the side.

My issue arise when I switch from SonicFoam to rhoCentralFoam to make sure I capture the shocks if any. The simulation always starts correctly, but after 10-30 timesteps (dt = 1e-9s to keep Co<0.2) I get this meessage:


Time = 8e-07

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 = 2.08375e-05, Final residual = 1.16963e-08, No Iterations 3
smoothSolver: Solving for Uy, Initial residual = 6.43467e-08, Final residual = 7.41012e-13, No Iterations 3
smoothSolver: Solving for Uz, Initial residual = 3.1202e-06, Final residual = 4.32488e-10, No Iterations 3
diagonal: Solving for rhoE, Initial residual = 0, Final residual = 0, No Iterations 0
smoothSolver: Solving for e, Initial residual = 9.57685e-06, Final residual = 9.57685e-06, No Iterations 0


--> FOAM FATAL ERROR: (openfoam-2406 patch=241212)
Negative initial temperature T0: -0.666552

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:erfectGas<Foam::specie> >; Type = Foam::sensibleInternalEnergy; Foam::scalar = double; Foam::species::thermo<Thermo, Type> = Foam::species::thermo<Foam::hConstThermo<Foam:er fectGas<Foam::specie> >, Foam::sensibleInternalEnergy>]
in file ./src/thermophysicalModels/specie/lnInclude/thermoI.H at line 57.

FOAM aborting

[stack trace]
=============
#1 Foam::error::simpleExit(int, bool) in /usr/lib/openfoam/openfoam2406/platforms/linux64GccDPInt32Opt/lib/libOpenFOAM.so
#2 ? in /usr/lib/openfoam/openfoam2406/platforms/linux64GccDPInt32Opt/lib/libfluidThermophysicalModels.so
#3 ? in /usr/lib/openfoam/openfoam2406/platforms/linux64GccDPInt32Opt/lib/libfluidThermophysicalModels.so
#4 ? in /usr/lib/openfoam/openfoam2406/platforms/linux64GccDPInt32Opt/lib/libfluidThermophysicalModels.so
#5 ? in /usr/lib/openfoam/openfoam2406/platforms/linux64GccDPInt32Opt/bin/rhoCentralFoam
#6 ? in /lib/x86_64-linux-gnu/libc.so.6
#7 __libc_start_main in /lib/x86_64-linux-gnu/libc.so.6
#8 ? in /usr/lib/openfoam/openfoam2406/platforms/linux64GccDPInt32Opt/bin/rhoCentralFoam
=============
Aborted (core dumped)


the line that concerns me the most is :
--> FOAM FATAL ERROR: (openfoam-2406 patch=241212)
Negative initial temperature T0: -0.666552

As I said, this error does not happen If I use sonicFoam. My divSchemes is:

divSchemes
{
default none;
div(phi,omega) Gauss limitedLinear 1; //SST
div(phi,k) Gauss upwind;
div(tauMC) Gauss linear;
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(phi,epsilon) Gauss upwind;
div(((rho*nuEff)*dev2(T(grad(U))))) Gauss linear;
}

Although I already tried many combinations. I believe my mesh is okay as it passed the checkMesh and Simular problem appears if I use only a blockMesh to generate a simple mesh, instead of my complex nozzle.

Has Anyone has the same problem?