Question

What is the range of y^+ in the log-law layer?

(a) 30<y^+<500

(b) 20<y^+<500

(c) 30<y^+<400

(d) 20<y^+<400

I had been asked this question in final exam.

This is a very interesting question from Turbulent Boundary Layer in section Turbulence Modelling of Computational Fluid Dynamics

Answer 1

Right choice is (a) 30<y^+<500

Explanation: The log-law layer extends outside the viscous or linear sub-layer. Here, both viscous and turbulent effects are important. It ranges between 30<y^+<500. It is called log-law layer because of the logarithmic relationship between u^+ and y^+.