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 thekay March 31, 2011 09:51

twoPhaseEulerFoam variables

Hi all

I was going through the code of twoPhaseEulerFoam and I have some questions about the variables in a part of alphaEqn.H and I'd be thankful if anyone could help me identify their use.

What is phic used for? It is initialised as
Code:

`surfaceScalarField phic = phi;`
What about alphaf? It is defined as
Code:

`surfaceScalarField alphaf = fvc::interpolate(alpha);`
And finally I cannot understand what phipp represents and how it is used.

Code:

`surfaceScalarField phipp = ppMagf*fvc::snGrad(alpha)*mesh.magSf();`
Cheers all

 alberto April 1, 2011 02:45

Hi,

phipp is a term used only if the ppMagf model is used. In such case, the momentum equation for phase a has an additional pressure gradient grad(pa). If you proceed as in the derivation of phase a "pressure equation", but keep that equation written in terms of alpha, understand the origin of phipp.

Hint: grad(pa) = G(alpha) * grad(alpha), where G(alpha) = ppMagf = d(pa)/d(alpha).

Best,

 k.kshitij November 26, 2011 00:48

Hi Alberto,

I have one question about the ppmagf's usage, according to my understanding the ppmagf model is implemented when the kinetic theory is off, ie when the value of g0 > 0.
Then why does its definition involve the kinetic theory particle pressure "pa". Or I'm wrong in getting this.
I'm a newbee to C++ and have not understood the code yet would you please clarify.