Simscale k-omega SST

Using SimScale Fluid Flow / CFD
1

Hi,

I have a question regarding the webinar of yesterday. If I am not wrong, it has been told that the k-omega sst model implemented in simscale requires a y+< 200. This sounds quite strange to me.
Indeed k-omega sst is a model obtained by blending two models, the k-omega and the k-epsilon (with more influence of the k-omega on the wall and the k-epsilon far from it).
I am not an expert of turbulence modelling implementation but theoretically speaking, if you have a too large y+ (like 200), the software will directly solve the k-epsilon equations, therefore switching your k-omega sst to a k-epsilon model.

I am maybe making some mistakes, but if possible it would be nice for me to get this clarification.

Thanks!

Fabio

2

Hello Fabio @Fabio88,

You are right, in order to properly resolve the shear layer in principle you need y+<10 (if not <1). Then again, by default we assume that you will be using wall functions in order to analytically resolve the shear layer. In that case we can go with y+ much higher, even up to 200.

Best,
Pawel