Turbulence

dale154 · November 25, 2015, 15:11

Hi, i have tested two turbulence models and just have a question about differences in solution.
I am modelling flow through a 2D compressor cascade.
Firstly i use k-omega turbulence and get a converging solution, however pressure values seem quite high.
However for some profiles i can't get a converging solution so i try SST-Transition and get a converging solution.
From this Pressure values seem more reasonable and velocity values are similar to that of the k-omega results.
I was wondering if anyone had any ideas on the differences observed between the two models?

(Note. 2D steady model, compressible, transonic flow with periodic boundaries).

I hope this is clear.
Thanks,
Dale.

CFDYourself · November 25, 2015, 16:01

hi dale,
The k-w model and the SST model are similar. the SST model blends the k-w model at the wall, and uses k-e model in the bulk. this plays to the strengths of the two models; k-w allows the flow to solve the boundary layer without relying on a wall function, while k-e model is more stable than k-w in the bulk.

November 25, 2015, 15:11	Turbulence	#1
dale154 New Member Join Date: Aug 2015 Posts: 22 Rep Power: 10	Hi, i have tested two turbulence models and just have a question about differences in solution. I am modelling flow through a 2D compressor cascade. Firstly i use k-omega turbulence and get a converging solution, however pressure values seem quite high. However for some profiles i can't get a converging solution so i try SST-Transition and get a converging solution. From this Pressure values seem more reasonable and velocity values are similar to that of the k-omega results. I was wondering if anyone had any ideas on the differences observed between the two models? (Note. 2D steady model, compressible, transonic flow with periodic boundaries). I hope this is clear. Thanks, Dale.

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November 25, 2015, 16:01		#2
CFDYourself Member Jim Join Date: May 2015 Posts: 47 Rep Power: 10	hi dale, The k-w model and the SST model are similar. the SST model blends the k-w model at the wall, and uses k-e model in the bulk. this plays to the strengths of the two models; k-w allows the flow to solve the boundary layer without relying on a wall function, while k-e model is more stable than k-w in the bulk.