Question

For unsteady turbulent flows, which of these averaging method is used?

(a) Time averaging

(b) Ensemble averaging

(c) Spatial averaging

(d) Volume averaging

I got this question during an online interview.

This key question is from Turbulence Modelling topic in chapter Turbulence Modelling of Computational Fluid Dynamics

Answer 1

Correct choice is (b) Ensemble averaging

Easy explanation: Time averaging is generally used to remove the fluctuations in RANS model. But it cannot be used when the problem is unsteady. In these cases, ensemble averaging is used to eliminate the fluctuations.