[sunilpatil]

Hello every,
I am curious to know that is there any viscosity limit bellow which we can use boussinesq hypothesis turbulence models (SA, ke, kW) and above which we have to use RSM turbulent models. Is there any dimensional number to identify these difference for quickly selecting turbulent model.
Thank you

[FMDenaro]

Originally Posted by sunilpatil

Hello every,
I am curious to know that is there any viscosity limit bellow which we can use boussinesq hypothesis turbulence models (SA, ke, kW) and above which we have to use RSM turbulent models. Is there any dimensional number to identify these difference for quickly selecting turbulent model.
Thank you

a physical reasoning guides to consider the minimum value to zero as negative values would imply an anti-diffusion effect that is somehow related to a backscatter of energy

[sunilpatil]

Hi denaro,
Can you please explain it. I am not understanding anti- diffusion effect and back scatter of energy.

[FMDenaro]

Originally Posted by sunilpatil

Hi denaro,
Can you please explain it. I am not understanding anti- diffusion effect and back scatter of energy.

immagine the diffusive flux of momentum, for positive values of the viscosity, it acts to smooth gradients. Conversely, an anti-diffusion due to negative values of the viscosity will tend to further increase a gradient.

[sunilpatil]

Hi denaro,
Thanks for your reply.