[adekian]

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]

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