Turbulence model for two phase incompressible flow

SailorLiu · March 31, 2016, 08:30

Dear Foamers,

I am trying to solve two phase (water and air) incompressible problems using interFoam. Basically, it is about floating structures in wind and waves. I have been using the kOmegaSST turbulence model. But I recently found that there is a large amount of turbulence near the free surface. I searched the forum and found one similar thread.

Quote:

There is no density in the formulation of the turbulence models, which leads to a huge diffusion of turbulence across the interface. This excess diffusion of turbulence (typically from air to water) dampens the wave very, very fast. In my case of studying wave breaking on a sloping beach, it lead to a dissipation of the wave energy without wave breaking - the wave simply disappeared.

It seems that density should be added to the k and omega equations. I browsed the code for the kOmegaSST model in OF2.4.x and density indeed is not included.

Does anybody know how to deal with this problem? Should I write my own turbulence model to include density into the turbulence euqations? Any help is appreciated.

Best wishes,

Yuanchuan Liu

neytirilover · April 2, 2016, 17:40

AFAIK the density*alpha term was added in KOmegaSST model in OF version 3.0.0, I don't know about previous versions tho, it might be easier just to upgrade to 3.0.0, than to write your own code and reinvent the wheel.

SailorLiu · April 4, 2016, 08:53

Hi neytirilover,

Thank you very much for your reply. I also read about the implementation of the new turbulence framework in OF-3.0.x. However, I am not quite sure how it can be used in the interFoam solver.

I tried a very simple case in OF-3.0.x, but it seems the solver is still using the old SST model without the density term as I only need to specify the scheme for the div(phi, k) term rather than a div(rhoPhi, k). If the turbulence equations have included the density term, at least it should request a discretisation scheme for the corresponding terms?

Do you know if the new updated turbulence model is enabled automatically for all solvers or further modification to the solver/case is needed?

Best wishes,

Yuanchuan Liu

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April 2, 2016, 17:40		#2
neytirilover New Member CH Xu Join Date: Jan 2013 Posts: 6 Rep Power: 13	AFAIK the density*alpha term was added in KOmegaSST model in OF version 3.0.0, I don't know about previous versions tho, it might be easier just to upgrade to 3.0.0, than to write your own code and reinvent the wheel.

April 4, 2016, 08:53		#3
SailorLiu Member Yuanchuan Liu Join Date: Oct 2012 Posts: 31 Rep Power: 14	Hi neytirilover, Thank you very much for your reply. I also read about the implementation of the new turbulence framework in OF-3.0.x. However, I am not quite sure how it can be used in the interFoam solver. I tried a very simple case in OF-3.0.x, but it seems the solver is still using the old SST model without the density term as I only need to specify the scheme for the div(phi, k) term rather than a div(rhoPhi, k). If the turbulence equations have included the density term, at least it should request a discretisation scheme for the corresponding terms? Do you know if the new updated turbulence model is enabled automatically for all solvers or further modification to the solver/case is needed? Best wishes, Yuanchuan Liu