# Something wrong in UEqns.H within twoPhaseEulerFoam

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March 15, 2011, 13:35
Something wrong in UEqns.H within twoPhaseEulerFoam
#1
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Charlie
Join Date: Dec 2010
Location: 415 Kinross Dr. Newark, DE 19711
Posts: 69
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I'm right now trying to understand how twoPhaseEulerFoam works, and get what they are erally solving. However, There seems something odd in the code.

Following is the source code for Ua and Ub in twoPhaseEulerFoam:

Quote:
in the code it seems very different for solving Ua and Ub (Noted as red in the quoted codes, compare line 10 and 52, line 24 and 61, line 41 and 79), However, We can define which phase is the dispersed phase in the "constant" files. Which means that we Ua and Ub should be solved in the similar way.

Or does openfoam has assigned use Ua to calculate dispersed phase and Ub for continuous phase? for example I define b as dispersed phase, then openfoam will solve Ua for b?

Also, note that only in Ueqn for a we can find the kinetic theory option. Is that true?

What's the momentum equation to guide this code? I'm relatively new to twoPhaseEulerFoam. Any help will be highly appreciated!

 June 24, 2011, 09:30 #2 New Member   Ulisses Join Date: Mar 2009 Location: Brazil Posts: 24 Rep Power: 6 Hi Charlie, I am using kinetic theory in twoPhaseEulerFoam but my solution diverges. Maybe it could be because of that you showed up. Have you achieved a conclusion about that? Thanks

June 24, 2011, 10:48
Try to reduce the timestep
#3
Member

Charlie
Join Date: Dec 2010
Location: 415 Kinross Dr. Newark, DE 19711
Posts: 69
Rep Power: 5
Hi,

There are two options to simulate the particle phase turbulence (In the code).

If we turn on the kinetic theory, then use kinetic theory to calculate the effective viscosity of particle phase.

If we turn the kinetic theory off, then we use turbulent response coefficient Ct to model the turbulent viscosity of particle phase.

As far as I'm concerned, the alphaEqn is more of significance leading to numerical divergence, since the alphaEqn in twoPhaseEulerFoam is nonlinear and also need to be bounded on both ends. try to refer to PhD thesis of Henrik Rusche, 2002.

About the phase selection, I just confirm to the convention, that is, use default setting, a as disperse phase, b as continuous phase.

Any question are welcomed.

Charlie

Quote:
 Originally Posted by ulisses Hi Charlie, I am using kinetic theory in twoPhaseEulerFoam but my solution diverges. Maybe it could be because of that you showed up. Have you achieved a conclusion about that? Thanks

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