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-   -   Doubt on yEqnH (http://www.cfd-online.com/Forums/openfoam-solving/58811-doubt-yeqnh.html)

 ash June 14, 2008 19:09

The yEqn.H files goes like thi

The yEqn.H files goes like this....

start of the yEqn.H file
################################################## #########

tmp<fv::convectionscheme<scalar> > mvConvection
(
fv::convectionScheme<scalar>::New
(
........
)
);

{
label inertIndex = -1;
volScalarField Yt = 0.0*Y[0];

for(label i=0; i<Y.size(); i++)
{
if (Y[i].name() != inertSpecie)
{
volScalarField& Yi = Y[i];

solve
(
fvm::ddt(rho, Yi)
+ mvConvection->fvmDiv(phi, Yi)
- fvm::laplacian(turbulence->muEff(), Yi)
==
kappa*chemistry.RR(i),
mesh.solver("Yi")
);

Yi.max(0.0);
Yt += Yi;
}
else
{
inertIndex = i;
}
}

Y[inertIndex] = scalar(1) - Yt;
Y[inertIndex].max(0.0);
}
################################################## ######
End of file yEqn.H

My question is what is the mathematical equation or expression for the yEqn.....

Is it, as follows.... please correct me if wrong.
d(rho,Yi)/dt + d(rho*u*Yi)/dx + d2(mu*Yi)dx2 = ??? (obviously, have written for the x-component)

I could guess the left hand side of the equation.... But i couldn't understand the right hand side of the equation...

Or to put my question in the other way, what are the terms "kappa*chemistry.RR(i),
mesh.solver("Yi")"

Help needed. Explain in a way, such that, whomsoever is new to openfoam can and I am new to foam..... http://www.cfd-online.com/OpenFOAM_D...part/happy.gif

 srinath June 15, 2008 00:11

Hi Which combustion solver

Hi

Which combustion solver are you referring to?reactingFoam?

In icoFoam, u have a similar expression, in the PISO loop
Ueqn.H()-- gives the non-diagonal + source terms of the matrix, but doesn't invlove the grad p term.
Here is a good reference for PISO in icoFoam, which u may find useful.
http://www.tfd.chalmers.se/~hani/kur...7/rhiechow.pdf

Do you have a reference for reactingFoam, trying to figure out the algo without a reference is very hard.

Cheers
Srinath

 ash June 15, 2008 05:32

I dont have any reference as s

I dont have any reference as such for the solver reactingFoam... someone please

 kaleekun June 15, 2008 14:36

Since this equation is species

Since this equation is species conservation equation, the right hand side must be the source term, that is, rate of production or consumption of the species. I have looked up for the fucnction chemistry.RR ----> it was stated as the chemical source term.

But I am not sure about the variable 'kappa' and the function, mesh.solver("Yi")
I guess someone should help him further

 villet June 15, 2008 15:31

As you can see the (laminar) c

As you can see the (laminar) chemical source term is multiplied by "kappa". This is a correction for turbulent reactive flows.

Next check out "chemistry.H" file and you can see how "kappa" is calculated. If the turbulence correction is not taken into account, "kappa" is set to "1.0".

I don't have a reference for the Chalmers PaSR model, but maybe there's someone else who can help you.

 sahm August 17, 2010 13:33

HI everyone,
I have a question . In the Yeqn equation, for diffusion of Yi, the coefficient used is Mu, why is that Mu? Why it's not D ( binary mass diffusion coefficient) ?
Can anybody give a reference for this?

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