[Kenna]

Hello everyone,

I am working on a welding simulation with argon as a inert gas, mixing with air from the surrounding.
The solver is compressibleTwoPhaseEulerFoam.
I am using openFoam 2.2.0.

The Temperaturs in this case vary from 300K to 20000K. Therefore I want to use the polynomial thermo Types to consider changes of the Properties (especially the viscosity).

My case works with non-Polynomial ThermoTypes.
I only tried to implement the Properties for the air with polynomials, but it never converges now.

thermoType
{
    type            heRhoThermo;
    mixture         pureMixture;
    transport       sutherland;//polynomial;//
    thermo          hConst;//hPolynomial;//
    equationOfState perfectGas;//icoPolynomial;//
    specie          specie;
    energy          sensibleEnthalpy;
}

mixture
{
    specie
    {
        nMoles      1;
        molWeight   28.949;
    }
    equationOfState
    {
//rhoCoeffs<8> (1.608 0 0 0 0 0 0 0);
rhoCoeffs<8> (0.9365 -6.3494e-04 1.7378e-7 -2.3819e-11 1.7798e-15 -7.3587e-20 1.58e-24 -1.3741e-29);
    }
    thermodynamics
    {
//CpCoeffs<8> (1005 0 0 0 0 0 0 0);
CpCoeffs<8> (-1.0526e+3 1.6398 2.6126e-04 -1.6356e-7 2.6306e-11 1.8049e-15 5.5509e-20 0);
Cp 1005;
Hf 0;
Sf 0;
    }    
    transport
    {
muCoeffs<8> (0.2325 -6.3198e-4 4.2443e-7 -7.9332e-11 7.3068e-15 -3.5628e-19 8.7685e-24 -8.5450e-29);
kappaCoeffs<8> (1.666667 0 0 0 0 0 0 0);
S 110.4;
As 1.716e-05;
Ts 273.15;
        mu          1.84e-05;
        Pr          0.656;
    }
}

When I run the case the number of pressure iteration goes up and states:

Max Ur Courant Number = 0.006956855
deltaT = 1.830625e-06
Time = 0.041002476

MULES: Solving for alpha1
MULES: Solving for alpha1
Dispersed phase volume fraction = 0.51264  Min(alpha1) = -1.971298e-23  Max(alpha1) = 1
DILUPBiCG:  Solving for h1, Initial residual = 5.480541e-05, Final residual = 2.571537e-09, No Iterations 2
DILUPBiCG:  Solving for h2, Initial residual = 3.958225e-06, Final residual = 3.044762e-10, No Iterations 2


--> 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/kennametal/OpenFOAM/OpenFOAM-2.2.0/src/thermophysicalModels/specie/lnInclude/thermoI.H at line 76.

FOAM aborting

#0  Foam::error::printStack(Foam::Ostream&) in "/home/kennametal/OpenFOAM/OpenFOAM-2.2.0/platforms/linuxGccDPOpt/lib/libOpenFOAM.so"
#1  Foam::error::abort() in "/home/kennametal/OpenFOAM/OpenFOAM-2.2.0/platforms/linuxGccDPOpt/lib/libOpenFOAM.so"
#2  Foam::species::thermo<Foam::hPolynomialThermo<Foam::icoPolynomial<Foam::specie, 8>, 8>, Foam::sensibleEnthalpy>::T(double, double, double, double (Foam::species::thermo<Foam::hPolynomialThermo<Foam::icoPolynomial<Foam::specie, 8>, 8>, Foam::sensibleEnthalpy>::*)(double, double) const, double (Foam::species::thermo<Foam::hPolynomialThermo<Foam::icoPolynomial<Foam::specie, 8>, 8>, Foam::sensibleEnthalpy>::*)(double, double) const, double (Foam::species::thermo<Foam::hPolynomialThermo<Foam::icoPolynomial<Foam::specie, 8>, 8>, Foam::sensibleEnthalpy>::*)(double) const) const in "/home/kennametal/OpenFOAM/OpenFOAM-2.2.0/platforms/linuxGccDPOpt/lib/libfluidThermophysicalModels.so"
#3  Foam::heRhoThermo<Foam::rhoThermo, Foam::pureMixture<Foam::polynomialTransport<Foam::species::thermo<Foam::hPolynomialThermo<Foam::icoPolynomial<Foam::specie, 8>, 8>, Foam::sensibleEnthalpy>, 8> > >::calculate() in "/home/kennametal/OpenFOAM/OpenFOAM-2.2.0/platforms/linuxGccDPOpt/lib/libfluidThermophysicalModels.so"
#4  Foam::heRhoThermo<Foam::rhoThermo, Foam::pureMixture<Foam::polynomialTransport<Foam::species::thermo<Foam::hPolynomialThermo<Foam::icoPolynomial<Foam::specie, 8>, 8>, Foam::sensibleEnthalpy>, 8> > >::correct() in "/home/kennametal/OpenFOAM/OpenFOAM-2.2.0/platforms/linuxGccDPOpt/lib/libfluidThermophysicalModels.so"
#5  
 in "/home/kennametal/OpenFOAM/OpenFOAM-2.2.0/platforms/linuxGccDPOpt/bin/my_compressibleTwoPhaseEulerFoam"
#6  __libc_start_main in "/lib/i386-linux-gnu/libc.so.6"
#7  
 in "/home/kennametal/OpenFOAM/OpenFOAM-2.2.0/platforms/linuxGccDPOpt/bin/my_compressibleTwoPhaseEulerFoam"

The less coeefficents I use the longer it calculates until it converges. But like this I have no benefit any more from this ThermoType.
Is there maybe a way to increase the number of iteration or to choose better solution/scheme-options?

I would appreciate your help.

Sincerly,
Kenna

[Kenna]

So, my guess is, because the temperature went in a little region lower than expected, my polynomial went into a negative zone and this is of course enough reason for a abort.

Also look here for some information, about increasing polynomial size.
http://www.cfd-online.com/Forums/ope...fficients.html