# SA Model Clarification

 Register Blogs Members List Search Today's Posts Mark Forums Read

 December 10, 2012, 00:00 SA Model Clarification #1 Senior Member   KGN Join Date: Oct 2009 Location: Chennai, India Posts: 120 Rep Power: 13 I am trying to simulate compressible flow through an air intake. I used SA model for turbulence. I defined "nuTilda" and "mut". When i run the problem, i get the following warning.. Then i define "k" and "epsilon". Even though i get the same warning. What actually does it mean. FOAM Warning : From function tmp SpalartAllmaras::k() const in file SpalartAllmaras/SpalartAllmaras.C at line 262 Turbulence kinetic energy not defined for Spalart-Allmaras model. Returning zero field Also when i tried to calculate the "yPlus". it asks for "nut". why? Cheers KGN

 December 11, 2012, 07:03 #2 Senior Member   KGN Join Date: Oct 2009 Location: Chennai, India Posts: 120 Rep Power: 13 Any reply ?

 July 31, 2014, 05:31 #3 New Member   yossi Join Date: Nov 2010 Posts: 8 Rep Power: 12 Hi, Have you found a solution?

July 31, 2014, 07:39
mutkWallFunction or mutUWallFunction
#4
Senior Member

Fabian Roesler
Join Date: Mar 2009
Location: Germany
Posts: 213
Rep Power: 15
Hi

Maybe I can help with this. Spalart Allmaras is a one equation turbulence model. It is not using turbulent kinetic energy k and a second variable like kEpsilon or kOmega models. Thus, the wall function for nut / mut have to be nutUWallFunction / mutUWallFunction instead of nutkWallFunction / mutkWallFunction for two equation models. So briefly:

Quote:
 Spalart Allmaras --> one equation model (nuTilda) nutUWallFunction (incompressible flow) mutUWallFunction (compressible flow) kOmega / kEpsilon --> two equation model (k and either epsilon or omega) nutkWallFunction (incompressible flow) mutkWallFunction (compressible flow)
Hope it helps.

Cheers

Fabian

 August 2, 2014, 05:46 #5 New Member   yossi Join Date: Nov 2010 Posts: 8 Rep Power: 12 I see, Thanks!