Question

The Reynolds number of a 3-D turbulent flow is 10^4. What is the number of grid points needed?

(a) 10^3

(b) 10^4

(c) 10^6

(d) 10^9

The question was posed to me during an online exam.

I want to ask this question from Direct Numerical Solution for Turbulent Models topic in chapter Turbulence Modelling of Computational Fluid Dynamics

Answer 1

The correct answer is (d) 10^9

The explanation: The ratio of the largest to the smallest length scale gives the number of grid points needed. The number of grid points needed in each direction is 10^3. The total number of grid points needed in all three directions (as the problem is 3-D) is 10^9.