[bioexplore]

Hi,

Can anybody tell me does the interphase drag force considered in interFoam? And what the difference between bubbleFoam and interFoam?

Thanks!

Jianye

[Andrea1984]

Hi Jianye,

you can find the interFoam formulation in the Henrik Rusche's Ph.D. thesis.

Andrea

[kwardle]

No. There is one velocity field shared by all phases in interFoam and it's derviatives (multiphaseInterFoam). bubbleFoam (and twoPhaseEulerFoam) uses Euler-Euler so each phase has it's own velocity field and inter-phase momentum transfer is supplied via drag formulations. A newer solver, multiphaseEulerFoam, is unique in that it does Euler-Euler for an arbitrary number of phases (with inter-phase drag), but it can also impose a sharp interface a la interFoam on any phase pairs. Hope this is useful info.

[bioexplore]

Thanks Andrea!

Originally Posted by Andrea1984

Hi Jianye,

you can find the interFoam formulation in the Henrik Rusche's Ph.D. thesis.

Andrea

But I think Henrik Rusche's Ph.D thesis dealing with bubbleFoam but not interFoam. Is this right? Can anyone know this give some explaination?

[bioexplore]

Thanks Kwardle!

Originally Posted by kwardle

No. There is one velocity field shared by all phases in interFoam and it's derviatives (multiphaseInterFoam). bubbleFoam (and twoPhaseEulerFoam) uses Euler-Euler so each phase has it's own velocity field and inter-phase momentum transfer is supplied via drag formulations. A newer solver, multiphaseEulerFoam, is unique in that it does Euler-Euler for an arbitrary number of phases (with inter-phase drag), but it can also impose a sharp interface a la interFoam on any phase pairs. Hope this is useful info.

You make it more clear!

What's my understanding is that (If I was wrong, please correct it!):
Because there is one share velocity field in interFoam, so there is no interphase momentum item derived in the UEqn, and the interface between liquid and gas is davanced by solving the alpha equation?
For bubbleFoam, the derived UEqns for each phase have the interphase momentum item, so when solving each phase's UEqn the interphase momentum item should also be given?

Is this correct?

[ziad]

interFoam is a Volume of Fluid solver so it solves one set of mixture Navier-Stokes equations with a volume fraction scalar transport equation that determines which phase you're dealing with. It does not account for interphase momentum transport because it is simply not part of the VOF mixture formulation.

It is described in Onno Ubink's PhD thesis, and definitely not Henrik Rusche's, as pointed out by kwardle. Check out equations 2.14 and 2.15 in Onno's thesis which can be found there http://powerlab.fsb.hr/ped/kturbo/Op...oUbbinkPhD.pdf

In bubbleFoam (and twoPhaseEulerFoam) you solve a full set of NS equations for each phase and couple them with the momentum coupling term which includes drag, lift and virtual mass. Turbulence is done with k-epsilon on the mixture.

[bioexplore]

Hi, Ziad, Thanks very much for your clearly explaination, It makes me more clear about the difference between interFoam and bubbleFoam.

[ziad]

You're quite welcome.

[santiagomarquezd]

Some clarifications,

1. Henrik Rusche's thesis deals both with VOF and Euler-Euler
2. VOF can be derived from Euler-Euler via the Mixture Model, giving which I call the Weller-VOF method, this explains why interFoam retains the relative velocity term in the alpha Eqn. and the necessity to go from volumetric flux formulation to mass flux formulation assembling the rhoPhi field. This is a key concept to understand the interFoam code.
3. As the guys told, the velocity is treated as a only one field in the momentum equations so that the interphase momentum exchange term vanishes (its expresion is , where is the relative velocity between phases p and q).

I give a full explanation of these issues in my PhD thesis which is in review, it will be available for the community by the end of March, 2013.

Regards.