[prasa]

Hai,

I have a question, why there is no iteration for velocity in reacting foam.


I'm runing the openfoam model with reacting foam for mixing of two gases without reaction. But unfortunatly, I can not see the iteration for U. As example,

diagonal: Solving for rho, Initial residual = 0, Final residual = 0, No Iterations 0
PIMPLE: iteration 1
DILUPBiCG: Solving for CH4, Initial residual = 9.70475e-05, Final residual = 1.12659e-10, No Iterations 1
DILUPBiCG: Solving for h, Initial residual = 7.69168e-05, Final residual = 1.13125e-09, No Iterations 1
min/max(T) = 284.895, 475.458
DICPCG: Solving for p, Initial residual = 5.49665e-05, Final residual = 7.40307e-10, No Iterations 1
diagonal: Solving for rho, Initial residual = 0, Final residual = 0, No Iterations 0
time step continuity errors : sum local = 2.2506e-06, global = 4.28088e-07, cumulative = 0.000749189
DICPCG: Solving for p, Initial residual = 9.12151e-09, Final residual = 9.12151e-09, No Iterations 0
diagonal: Solving for rho, Initial residual = 0, Final residual = 0, No Iterations 0
time step continuity errors : sum local = 2.25063e-06, global = 4.28091e-07, cumulative = 0.000749617
ExecutionTime = 2727.74 s ClockTime = 2729 s



Here it has calculated for P,h,and CH4 only.




But in icoFom model it shows iteration for Velocity. example,

smoothSolver: Solving for Ux, Initial residual = 2.32737e-07, Final residual = 2.32737e-07, No Iterations 0
smoothSolver: Solving for Uy, Initial residual = 5.07002e-07, Final residual = 5.07002e-07, No Iterations 0
DICPCG: Solving for p, Initial residual = 1.0281e-06, Final residual = 2.77237e-07, No Iterations 1
time step continuity errors : sum local = 4.0374e-09, global = -9.0204e-19, cumulative = -2.44407e-18
DICPCG: Solving for p, Initial residual = 5.31987e-07, Final residual = 5.31987e-07, No Iterations 0
time step continuity errors : sum local = 6.12557e-09, global = -3.93738e-20, cumulative = -2.48344e-18
ExecutionTime = 0.17 s ClockTime = 1 s



What is the reason for it? Anyone know the reason for this difference ?

Best Regards,
Prasanna.

[sharonyue]

Hi Prasanna,

Sometimes you dont need to solve velocity, but u must construct velocity matrix. Check it in your pimple solution (fvSolution), I estimate the momentum predictor is switched off.

Best,

[prasa]

Hai Dongyue Li,

Thank you for the comment. Your guess is exactly correct.

I have switch off momentumpredictor .

I will show it bellow , just to if someone else need

reactingFoam > fvSolution >PIMPLE

{
momentumPredictor yes;
nOuterCorrectors 1;
nCorrectors 2;
nNonOrthogonalCorrectors 0;
}





I have another question with runing in reactingFoam.

It gives me following error, This error comes after few iterations.




--> 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 /home/openfoam/OpenFOAM/OpenFOAM-2.4.0/src/thermophysicalModels/specie/lnInclude/thermoI.H at line 76.

FOAM aborting

#0 Foam::error:rintStack(Foam::Ostream&) at ??:?
#1 Foam::error::abort() at ??:?
#2 Foam::species::thermo<Foam::hConstThermo<Foam:er fectGas<Foam::specie> >, Foam::sensibleEnthalpy>::THs(double, double, double) const at ??:?
#3 Foam::hePsiThermo<Foam:siReactionThermo, Foam::SpecieMixture<Foam::reactingMixture<Foam::co nstTransport<Foam::species::thermo<Foam::hConstThe rmo<Foam:erfectGas<Foam::specie> >, Foam::sensibleEnthalpy> > > > >::calculate() at ??:?
#4 Foam::hePsiThermo<Foam:siReactionThermo, Foam::SpecieMixture<Foam::reactingMixture<Foam::co nstTransport<Foam::species::thermo<Foam::hConstThe rmo<Foam:erfectGas<Foam::specie> >, Foam::sensibleEnthalpy> > > > >::correct() at ??:?
#5 ? at ??:?
#6 __libc_start_main in "/lib/x86_64-linux-gnu/libc.so.6"
#7 ? at ??:?
Aborted (core dumped)
meeseeks@meeseeks-Precision-Tower-7810:~/prasa/run16_withstatic_mixer$ paraview
ERROR: In /build/buildd/paraview-4.0.1/VTK/IO/Geometry/vtkOpenFOAMReader.cxx, line 8464
vtkPOpenFOAMReader (0x4105ab0): /home/meeseeks/prasa/run16_withstatic_mixer/system/fvSolution contains no timestep data.



Do you have a idea about this ?

Regards,
Prasanna.

[sharonyue]

Well, it just blow up. I have no idea about this. If switching off momentum predictor makes it blowing up, just switch it off. In some cases momentum predictor is not good for convergence.