Question

Which of these correct about the LES method?

(a) Navier-Stokes equation is not needed

(b) Small turbulent models are directly simulated

(c) Sub-grid scale models are used for small turbulent scales

(d) Sub-grid scale models are used for large turbulent scales

This question was addressed to me in an internship interview.

My doubt is from Turbulence Modelling in section Turbulence Modelling of Computational Fluid Dynamics

Answer 1

The correct option is (c) Sub-grid scale models are used for small turbulent scales

The explanation: Large scale turbulent structures are directly simulated and the small scales are simulated using sub-grid models. A spatial statistical filter is used to filter the Navier-Stokes equation to determine which scale to keep and which to discard.