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-   -   Exceeded iterations for high molar masses. (http://www.cfd-online.com/Forums/openfoam-solving/125751-exceeded-iterations-high-molar-masses.html)

CoolKau October 30, 2013 08:12

Exceeded iterations for high molar masses.
 
I have been running a simulation for quite a while. I tried different pressures, slightly different geometries, boundary conditions. I used Hydrogen and never ran into problems. Now, I wanted to repeat the simulations in Argon. So I changed the thermo properties and the simulation crashes always, no matter what I try. I identified the error to be connected to the molar mass. With all parameters the same but the molar mass the error occurs when the molar mass exceeds 8.

The error is posted below. It always occurs at the second time step.

I tried various time steps and initial conditions. I tried to run the simulation with hydrogen first and then switched the molar mass. I played with the grid size.

I used OpenFoam 2.2.1, sonicFoam with
thermoType
{
type hePsiThermo;
mixture pureMixture;
transport const;
thermo eConst;
equationOfState perfectGas;
specie specie;
energy sensibleInternalEnergy;
}


If needed I am happy to give more information about the setup.

I am sorry if my question might be silly as I am not an expert in OpenFoam.
But thank you very much for your help in advance.




Time = 1e-11

Courant Number mean: 0 max: 0
diagonal: Solving for rho, Initial residual = 0, Final residual = 0, No Iterations 0
DILUPBiCG: Solving for Ux, Initial residual = 1, Final residual = 2.68031e-06, No Iterations 1
DILUPBiCG: Solving for Uy, Initial residual = 1, Final residual = 1.4784e-07, No Iterations 1
DILUPBiCG: Solving for e, Initial residual = 1, Final residual = 4.40894e-08, No Iterations 2
DILUPBiCG: Solving for p, Initial residual = 1, Final residual = 9.96913e-14, No Iterations 1
diagonal: Solving for rho, Initial residual = 0, Final residual = 0, No Iterations 0
time step continuity errors : sum local = 3.36116e-15, global = -3.32923e-15, cumulative = -3.32923e-15
DILUPBiCG: Solving for p, Initial residual = 6.26642e-17, Final residual = 6.26642e-17, No Iterations 0
diagonal: Solving for rho, Initial residual = 0, Final residual = 0, No Iterations 0
time step continuity errors : sum local = 5.78765e-14, global = -3.32853e-15, cumulative = -6.65776e-15
DILUPBiCG: Solving for omega, Initial residual = 0.000975322, Final residual = 1.44466e-12, No Iterations 2
DILUPBiCG: Solving for k, Initial residual = 1, Final residual = 3.6463e-09, No Iterations 2
ExecutionTime = 0.23 s ClockTime = 0 s

Time = 2e-11

Courant Number mean: 3.25537e-14 max: 1.0717e-10
diagonal: Solving for rho, Initial residual = 0, Final residual = 0, No Iterations 0
DILUPBiCG: Solving for Ux, Initial residual = 0.334038, Final residual = 1.4194e-08, No Iterations 1
DILUPBiCG: Solving for Uy, Initial residual = 0.318687, Final residual = 6.53075e-09, No Iterations 1
DILUPBiCG: Solving for e, Initial residual = 7.92849e-05, Final residual = 1.35329e-09, No Iterations 1


--> FOAM FATAL ERROR:
Maximum number of iterations exceeded

From function thermo<Thermo, Type>::T(scalar f, scalar T0, scalar (thermo<Thermo, Type>::*F)(const scalar) const, scalar (thermo<Thermo, Type>::*dFdT)(const scalar) const, scalar (thermo<Thermo, Type>::*limit)(const scalar) const) const
in file /apps/OpenFOAM//OpenFOAM-2.2.1/src/thermophysicalModels/specie/lnInclude/thermoI.H at line 76.

CoolKau October 31, 2013 15:07

After going through all the different input parameters i realized that I set the initial internal temperature too low. This is already indicated by the Thermo function failing.

High molar masses seem to be more sensitive to temperature.


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