___________ creates a problem in the SGS models. A. Low Reynolds

creates-a-problem-in-the-sgs-models-a-low-reynolds

___________ creates a problem in the SGS models.

A. Low Reynolds number flows

B. High Reynolds number flows

C. Anisotropic flow near the wall

D. Viscous flow near the wall

The question was asked during an interview.

Query is from Turbulence Modelling topic in chapter Turbulence Modelling of Computational Fluid Dynamics

Right option is C. Anisotropic flow near the wall

To explain: Near the wall, the flow structure is very anisotropic. Here, regions of low and high-speed fluids are created. This needs a highly anisotropic grid. But, the choice of length scale is restricted by the cut-off width. This poses a problem in the SGS models.