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CFD_10 May 27, 2019 13:48
Homogenous and isotropic turbulence in RANS modeling
 
hello
I have a question about turbulence models in the Reynolds Averaging Navier Stokes method implemented in most CFD softwares.


Let's limit the scope only to k-epsilon and k-omega models,

Do they suppose a homogeneous and isotropic turbulence?
if so then as far as I know: A flow is said to be homogenous if there are no spatial gradients in any averaged gradients. and a turbulent flow is said to be isotropic if rotation and buoyancy are not important and there is no mean flow.


Any details please?

FMDenaro May 27, 2019 14:07
Quote:
Originally Posted by CFD_10 (Post 734895)
hello
I have a question about turbulence models in the Reynolds Averaging Navier Stokes method implemented in most CFD softwares.


Let's limit the scope only to k-epsilon and k-omega models,

Do they suppose a homogeneous and isotropic turbulence?
if so then as far as I know: A flow is said to be homogenous if there are no spatial gradients in any averaged gradients. and a turbulent flow is said to be isotropic if rotation and buoyancy are not important and there is no mean flow.


Could you please answer my question?



No, RANS formulations suppose only fully developed turbulence

sbaffini May 27, 2019 16:38
Only some (not all) coefficients are typically calibrated against HIT.


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