SAS: scale adaptative simulation?

November 21, 2007, 19:35

i have to carry out a simulation of unsteady turbine flow ,and i see that CFX includes a new model SAS .i'm wondering if it's faithful and costs in computational time.

November 23, 2007, 14:19

Hi Amine,

The SAS-SST model was promoted from beta to release capabilty in version 11 and it suitable for unsteady flows. It can resolve large eddies in transient simulations, but doesn't suffer the problems of LES and DES type methods.

In terms of computational cost, it is solving a k and omega equation, which more expensive than LES (which uses an algebraic formulation for eddy viscosity at the sub-grid level), but it returns physically realistic results on much coarser grids. You can get away with standard inflation, etc. at walls (as opposed to isotropic elements for LES), which means your grid can be an order of magnitude smaller for the same accuracy.

There are a number of papers from Dr. Florian Menter on the topic.

-CycLone

November 21, 2007, 19:35	SAS: scale adaptative simulation?	#1
amine Guest Posts: n/a	i have to carry out a simulation of unsteady turbine flow ,and i see that CFX includes a new model SAS .i'm wondering if it's faithful and costs in computational time.

November 23, 2007, 14:19	Re: SAS: scale adaptative simulation?	#2
CycLone Guest Posts: n/a	Hi Amine, The SAS-SST model was promoted from beta to release capabilty in version 11 and it suitable for unsteady flows. It can resolve large eddies in transient simulations, but doesn't suffer the problems of LES and DES type methods. In terms of computational cost, it is solving a k and omega equation, which more expensive than LES (which uses an algebraic formulation for eddy viscosity at the sub-grid level), but it returns physically realistic results on much coarser grids. You can get away with standard inflation, etc. at walls (as opposed to isotropic elements for LES), which means your grid can be an order of magnitude smaller for the same accuracy. There are a number of papers from Dr. Florian Menter on the topic. -CycLone

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