Module 2 :
Lecture 5 : Kolmogorov Hypothesis and Energy Cascade
 


The Kolmogorov micro scales are formed using the dissipation rate per unit mass and the Kinematic viscosity ν .

 

Length scale,

Time scale,

Velocity scale,

 

We define as Reynolds number

~ ~ ~

where velocity scale, L integral length scale and λ Taylor microscale

Let us estimate Kolmogorov's length scale

Imagine a channel flow

Figure 5.1

 

Assume Isotropy, i.e.,

~ ~

 

Kolmogorov Length Scale

         ~
  

 

Let us take

U = 10 m/s, D =1m,
Re = 6.5 × 10 5 , Tu = 0.2

 


      = 0.38mm