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-   -   GammaEqn and UEqn in interFoam (http://www.cfd-online.com/Forums/openfoam-solving/59749-gammaeqn-ueqn-interfoam.html)

adekian April 10, 2007 11:06

Dear all, Could anyone expl
 
Dear all,

Could anyone explain the following terms in interFoam solver?

1. In gammaEqn.H
What does the third term on the l.h.s of gammaEqn mean?

fvm::div
(-fvc::flux(-phir, scalar(1) - gamma, gammarScheme),
gamma,
gammarScheme)

Is it something like correction term to maintain mass conservation? From what is this term derived?

2. In UEqn.H

What does the term
(fvc::grad(U) & fvc::grad(muf))
on the l.h.s of UEqn account for?

I've been browsing this forum for answers, but so far couldn't find any.

Thank you,

brian

hjasak April 11, 2007 02:03

Without fussing about it too m
 
Without fussing about it too much:

- in the momentum equation, (fvc::grad(U) & fvc::grad(muf)) is a different formulation of the
div(mu (grad U)^T) term, which does not go away when mu is non-constant

- in the gamma equation the term
(-fvc::flux(-phir, scalar(1) - gamma is an alternative form of the relative velocity term. This is what you get when you reformulate

ddt(gamma) + div(gamma U_gamma) = 0

in the form that will use the volume velocity U instead of phase velocity gamma.

For more details, I would recommend a good Thesis from dr. Henrik Rusche:

@PhdThesis{Rusche:PhD,
author = {Rusche, H.},
title = {Computational fluid dynamics of dispersed two-phase
flows at high phase fractions},
school = {Imperial College, University of London},
year = 2003
}


Hrv


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