Question

What do the length, velocity and time-scale ratios mean?

(a) The ratio of large-scale and characteristic properties

(b) The ratio of small-scale and characteristic properties

(c) The ratio of small and large scale eddies

(d) The ratio of actual and characteristic properties

This question was addressed to me in class test.

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

Answer 1

The correct answer is (c) The ratio of small and large scale eddies

Explanation: The time-scale ratio is the ratio between small-scale time (of small-scale eddies) and large-scale time (of small-scale eddies). Similarly, the length and velocity-scale ratios are also the ratios between small and large-scale lengths and velocities.