Week 4 - Turbulence and fractals

Question 1

They reynold number can be seen as the ratio of the inertial forces to ____ .

Answer 1

viscous forces. Large Re (over 2000) leads to turbulent flow. Low Re (under 20) leads to laminar flow.

Question 2

What is the difference between Kolmogorov’s and Burgers’ turbulence theories?

Answer 2

Kolmogorov: compressible (supersonic), sigma \propto R^(1/3)

Burgers: incompressible (subsonic), sigma \propto R^(1/2)

Question 3

State Kolmogorov’s law

Answer 3

Homogenous, isotropic, incompressible (less eddies and acoustic noise) and turbulent flows exhibit a dissipationless cascade of energy from the largest scale down to the scale at which viscous dissipation becomes important

Question 4

What are fractals?

Answer 4

Ensembles that can be defined by their self-similarity

Question 5

How is the Hausdorff dimension D defined?

Answer 5

As M propto R^D