[nakul]

Hi,
I am trying to run a case using reactingFOAM. But I am getting the following error:

FOAM FATAL ERROR : attempt to use janafThermo<equationofstate> out of temperature range 200 -> 5000; T = 195.559.

From function janafThermo<equationofstate>::checkT(const scalar T) const
in file /home/dm2/henry/OpenFOAM/OpenFOAM-1.2/src/thermophysicalModels/specie/lnInclude/ janafThermoI.H at line 73

The temperatures that I have supplied as BC are 1000K and 600K for O2 and H2 respectively. (Its H2-O2 combustion.)

My Courant No. is 0.2 and my max. cell skewness = 0.66838.
My "checkMesh" results are all OK.

Can anybody please tell me where am I going wrong?

[kalle]

Hi,

this is a common problem. For me it was always caused by erroneous BC's.

Though this user does not get janaf errors, you can see how BC's can be set:

http://www.cfd-online.com/Forums/ope...onditions.html (inletOutlet BC at outlets)

Other problems may be misconfigured inlets/initial condition. Please check that initally every cell and face have a proper mixture.

K

[nakul]

Thanx Karl for such an early reply. I changed my BC accordingly.

But I have few doubts :
1) What should be the BC for k and epsilon as my problem also employs k-epsilon turbulence model?

2) At the inlet for air, the air is moving with certain velocity so wether the BC for pressure should be "total pressure" or the "fixedValue" of known static presure? The airspeed at inlet is known to me.

3) Moreover my case also includes compressibiltiy. So in your opinion should there be any changes in BC.

Actually I didn't specified exactly the BC as you directed in that link, rather I have tweaked them a little bit, because the solver was giving the same error earlier than the time, when it used to blow with previously specified BC. So could you please tell me the logic behind changing these BC or you may refer me to some study material if possible!!

[kalle]

Hi,

1) For k and eps, I would use the same types as for other scalars (except p), that is: prescribed value at inlet and inletOutlet at outlets.

2, 3) For incompressible (in this case low-Mach number cases) or weakly compressible, I would use zeroGradient at inlet and totalPressure at outlet. If you are running hi-Mach numbers, you would need other BC's. Can't help you much there, unfortunately. If you by compressibility mean mainly density dependence on temperature, and pressure fluctuations remain low, I would go for a low-Mach number formulation, where rho(T, Yi, h) and you introduce a constant global pressure in the state equation.

Logic behind BC's: To have a well posed system which gives you what you want could be a pragmatic logic :-)

K

[nakul]

Thanx Karl !

Actually I do have high Mach no.flow of order of Mach No. =2.5.

Do you think "waveTransmissive" BC for pressure in super-sonic flow good?

Could you tell me any references, if possible?

If anybody else can help, it would be greatly appreciated!!!

[yash.aesi]

Greetings oll,
I am using OF-2.2 and tried to solve my case using reactingFoam solver with PasR model . i am getting the temperature profile almost as required but i am not getting the mass fraction of the products as desired . it coming almost double of what i desire.

i checked my BC's many times and i don't think there is any mistake . i am attaching the files plz have a look .
so can anybody tell me then where i am doing wrong ??

Thanks in advance


Regards ,
Sonu

[simorgh1328]

i want to simulate a diffusion flame with reactingfoam the uniform y exit velocity for CH4 is 0.066 after some time steps the pressure contour show strange gradient in flow filed
can anyone help me?

velocity file
// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //

dimensions [0 1 -1 0 0 0 0];

internalField uniform (0 0 0);

boundaryField
{
inletfuel
{
type fixedValue;
value uniform (0 0.066 0);
}
inletair
{
type zeroGradient;
}
outlet
{
type pressureInletOutletVelocity;
value uniform (0 0 0);
}

surround
{
type zeroGradient;
}
burnertip
{
type fixedValue;
value uniform (0 0 0);
}
front
{
type wedge;
}
back
{
type wedge;
}
}


// ************************************************** *********************** //
pressure file:


dimensions [1 -1 -2 0 0 0 0];

internalField uniform 101325;

boundaryField
{
inletfuel
{
type zeroGradient;
}
inletair
{
type zeroGradient;
}
outlet
{
type totalPressure;
p0 $internalField;
}

surround
{
type zeroGradient;
}
burnertip
{
type zeroGradient;
}
front
{
type wedge;
}
back
{
type wedge;
}
}