SST eddy viscosity in CFX

czm28 · March 12, 2017, 19:45

Hi,

The equation of the eddy viscosity for SST turbulence model is
111.jpg

I want to modify the density in the equation for cavitation analysis.

I would like to ask that how to type the eddy viscosity in CFX by CEL language?

Thank you.

ghorrocks · March 13, 2017, 04:56

I think you will need to do your own turbulence model to do this. You can do this using additional variables and CEL. Then you can define viscosity to be a function of anything you like.

But before you do: turbulence models were developed to model single phase flows. It is an active area of research how to develop a useful turbulence model for multiphase flows - in other words no turbulence model currently exists that handles multiphase flows well. I can assure you that simply changing to eddy viscosity term in an existing model is not going to work very well, there are much more fundamental (and complex) problems than that to address.

So I would not bother. But if you still wish to do so, let us know how you go.

March 12, 2017, 19:45	SST eddy viscosity in CFX	#1
czm28 New Member zhenmu Join Date: Dec 2014 Posts: 4 Rep Power: 11	Hi, The equation of the eddy viscosity for SST turbulence model is 111.jpg I want to modify the density in the equation for cavitation analysis. I would like to ask that how to type the eddy viscosity in CFX by CEL language? Thank you.

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March 13, 2017, 04:56		#2
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,703 Rep Power: 143	I think you will need to do your own turbulence model to do this. You can do this using additional variables and CEL. Then you can define viscosity to be a function of anything you like. But before you do: turbulence models were developed to model single phase flows. It is an active area of research how to develop a useful turbulence model for multiphase flows - in other words no turbulence model currently exists that handles multiphase flows well. I can assure you that simply changing to eddy viscosity term in an existing model is not going to work very well, there are much more fundamental (and complex) problems than that to address. So I would not bother. But if you still wish to do so, let us know how you go.