[Seb_Ve]

Hello,

I'm quite new to OpenFoam and having some problems with my case. I am using the solver pimpleCentralFoam and set everything up so far. But the Problem is that the simulations stops without any error message and I don't know why.

I hope you can help me and thanks in advance!

Whats in my terminal:

/*---------------------------------------------------------------------------*\
| ========= | |
| \\ / F ield | OpenFOAM: The Open Source CFD Toolbox |
| \\ / O peration | Version: 4.1 |
| \\ / A nd | Web: www.OpenFOAM.org |
| \\/ M anipulation | |
\*---------------------------------------------------------------------------*/
Build : 4.1
Exec : pimpleCentralFoam
Date : Dec 19 2017
Time : 20:31:14
Host : "ThinkPad13"
PID : 229
Case : /mnt/c/Projektarbeit/BasedOnBackwardStep_1
nProcs : 1
sigFpe : Enabling floating point exception trapping (FOAM_SIGFPE).
fileModificationChecking : Monitoring run-time modified files using timeStampMaster
allowSystemOperations : Allowing user-supplied system call operations

// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
Create time

Create mesh for time = 0


PIMPLE: no residual control data found. Calculations will employ 3 corrector loops

Reading thermophysical properties

Selecting thermodynamics package
{
type hePsiThermo;
mixture pureMixture;
transport const;
thermo hConst;
equationOfState perfectGas;
specie specie;
energy sensibleEnthalpy;
}

Reading field U

Creating field kinetic energy K

Selecting finite volume kappaFunction type standardMachToAcCourantRatio
Creating turbulence model

Selecting turbulence model type RAS
Selecting RAS turbulence model kOmega
kOmegaCoeffs
{
betaStar 0.09;
beta 0.072;
gamma 0.52;
alphaK 0.5;
alphaOmega 0.5;
}

No finite volume options present

No MRF models present

Marking cells with bad quality to limit pressure gradient
max/min FaceAcCourant: 0.0721447/2.28841e-05
max/min Maf: 0/0
max/min kappa: 0/0
Courant Number max : 0 velocity magnitude: 0

Starting time loop

Mean and max Characteristic Courant Numbers = 0.000733386 0.0721447
Courant Number max : 0 velocity magnitude: 0
deltaT = 0.001
Time = 0.001

diagonal: Solving for rho, Initial residual = 0, Final residual = 0, No Iterations 0
rho max/min : 4.09775 / 0.819549
PIMPLE: iteration 1
DILUPBiCGStab: Solving for omega, Initial residual = 0.334139, Final residual = 5.6778e-16, No Iterations 111
DILUPBiCGStab: Solving for k, Initial residual = 1, Final residual = 9.11384e-16, No Iterations 31
bounding k, min: -0.363994 max: 0.213129 average: 0.000267676
DILUPBiCGStab: Solving for h, Initial residual = 0.651609, Final residual = 6.78465e-16, No Iterations 21
max/min T: 425/425
DILUPBiCGStab: Solving for p, Initial residual = 0.000486029, Final residual = 6.1208e-16, No Iterations 301
max(U): (297.448 1.39344e-12 523.822)
max/min p: 500000/100000
diagonal: Solving for rho, Initial residual = 0, Final residual = 0, No Iterations 0
rho max/min : 4.09767 / 0.819711
time step continuity errors : sum local = 2.14872e-09, global = -5.95084e-12, cumulative = 0
max/min FaceAcCourant: 62001/65.7294
max/min Maf: 1.52823/0
max/min kappa: 0.00481344/0
PIMPLE: iteration 2
DILUPBiCGStab: Solving for omega, Initial residual = 0.666186, Final residual = 1.91444e-17, No Iterations 3
bounding omega, min: -1.71684 max: 2.2804e+08 average: 430618
DILUPBiCGStab: Solving for k, Initial residual = 0.993415, Final residual = 5.20457e-16, No Iterations 33
DILUPBiCGStab: Solving for h, Initial residual = 0.814062, Final residual = 28.3773, No Iterations 1001
max/min T: 3.58195e+07/-7.03686e+07

[piu58]

The number of iteration just at the start is much to high. The system in in an instable state. As ypu can see, T raises to very high values. I recommend first reducing delta t to a much smaller value. It doesn't count to start wit for instance 1e-7 i you use automatic time step control.

[Seb_Ve]

Hi,
thanks for your answer. I already had very small time steps and the only difference was that the Courant number was very small (e-20). But the overal "result" was the same and the Simulation stopped too.

[piu58]

That doesn't seem to be true:

Mean and max Characteristic Courant Numbers = 0.000733386 0.0721447
Courant Number max : 0 velocity magnitude: 0
deltaT = 0.001
Time = 0.001

[Seb_Ve]

Hallo, wir können das ganze ja wahrscheinlich auch auf Deutsch machen.

Ich meinte, dass ich bereits vorher einige Versuche mit kleineren Zeitschritten gemacht habe. Bei der, die ich hier hinein gestellt habe, bin ich etwas größer geworden, da die Courant Zahl extrem klein war, allerdings waren die Ergebnisse in beiden Simulationen gleich.