Question

What is the range of length and frequency of the Kolmogorov micro-scale eddies respectively?

(a) 0.1 to 1 mm, around 1 kHz

(b) 1-10 mm, around 10 kHz

(c) 0.01 to 0.1 mm, around 10 kHz

(d) around 10 mm, 0.1 to 0.01 kHz

The question was asked in final exam.

My question is taken from Turbulence Modelling topic in section Turbulence Modelling of Computational Fluid Dynamics

Answer 1

Correct option is (c) 0.01 to 0.1 mm, around 10 kHz

Easy explanation: The smallest scales of motion in a turbulent flow is called the Kolmogorov micro-scale. They have a wavelength of around 0.01 to 0.1 mm and frequencies around 10 kiloHertz. They have Reynolds number very near to one.