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-   -   How to choose the YPLUS value in two-phase flows? (http://www.cfd-online.com/Forums/fluent/43705-how-choose-yplus-value-two-phase-flows.html)

Niewlande February 10, 2007 20:29

How to choose the YPLUS value in two-phase flows?
 
For two-phase Euler-Euler multiphase model + turbulence model, how to select the reported "yplus" values for meeting the requirement of law-of-the-wall?

I mean, there are two "yplus" values from different phases (say, YPLUS for air & solid). Then, which one should be chosen for the grid adjustment?

Especially, for the MIXTURE and DISPERSED models (k-epsilon multiphase turbulence model), how to make decision for the YPLUS value?

Please give your idea.

undziabundzia December 7, 2015 11:22

Anyone knows ? Shall we move that topic, to "meshing problems". I need very much informations, about Yplus wall for water and air, becouse i working on two-phase flow around ship.

Thank You for sharing Your knowledge. You are great !!

LuckyTran December 7, 2015 16:08

There is no ambiguity in the meaning or definition of y+ for two-phase flows. Just because there may be two different phases in the domain, at a particular location the fluid can only be 1 phase. The exception is the VOF model which allows properties of different phases to be blurred together.

As for post-processing, there really is only one y+ value for the wall adjacent cell (whatever the wall adjacent value is). One y+ will be undefined for the phase that doesn't exist at the wall.

Meshing is no different than single-phase simulation. If you want to predict the grid requirements, then that always requires some knowledge of the expected flow field. Otherwise you can do trial-and-error.

undziabundzia December 7, 2015 16:43

Thank You for your reply, Friend.

So If I have Volume of Fluid with Air and Water, that have diffrent y+ from calculator. Which Y+ should I choose ?


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