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-   -   slip ratio between gas/liquid (https://www.cfd-online.com/Forums/openfoam/79233-slip-ratio-between-gas-liquid.html)

Robat August 17, 2010 12:11

slip ratio between gas/liquid
 
Hi foamers!

I have a two phase model in LesInterFoam, where I need to to know the velocity for each phase (of course besides the pressure loss).
My idea was to create an additional volume flux field for one single phase like "phiLiq" via gamma(or alpha) field.
I've made a "elbow-case" like pipe (a gas flow with liquid injection) to test my idea, but it not delivered me a slip ratio.

Does anybody know a good strategy or at least could give me a hint from which value I could get the information to calculate the gas slip ?

bests,
Robert

P.S.: This might be interesting for evaporation models like interDymFoam.

holger_marschall August 17, 2010 16:54

Quote:

Originally Posted by Robat (Post 271755)
I have a two phase model in LesInterFoam, where I need to to know the velocity for each phase (of course besides the pressure loss).

Hi Robert,

interFoam is based upon the homogeneous mixture assumption. In consequence you have to live with only a mixture velocity, which in turn demands for a high resolution for both the interfacial morphology (e.g. curvature) and boundary layer.
To evaluate a reasonable local slip velocity (i.e. for under-resolved boundary layers) would need a rewrite of the solver + theoretical work considering phase interaction and interchange...

As a start you might consider the work of M. Wörner and W. Sabisch, references of whom can be found here: http://bibliothek.fzk.de/zb/berichte/FZKA6889.pdf

In case you have any further questions let me know... I am on another approach considering an interfacial flow solver employing two momentum balances, thus inherently enabling for a interfacial phase slip.

best regards,

Robat August 18, 2010 05:41

Thanks for your quick reply.

I go to check the work of these people.
I'll keep you informed, if I find a good solution.

bests,
Robert

holger_marschall August 18, 2010 09:05

Sure, you are welcome...
Look out for VA-VOF as this method accounts for a phase slip (momentum drift flux term).

best,


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