CFD Online Discussion Forums

CFD Online Discussion Forums (
-   OpenFOAM (
-   -   SA Model Clarification (

mecbe2002 December 10, 2012 01:00

SA Model Clarification
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<volScalarField> 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?


mecbe2002 December 11, 2012 08:03

Any reply ?

yossi July 31, 2014 05:31


Have you found a solution?

fabian_roesler July 31, 2014 07:39

mutkWallFunction or mutUWallFunction

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:


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.



yossi August 2, 2014 05:46

I see,


All times are GMT -4. The time now is 15:08.