Question

What is the mixing length for the outer layer of a 2-D turbulent boundary layer?

(a) 0.09 times the boundary layer thickness

(b) 0.08 times the boundary layer thickness

(c) 0.07 times the boundary layer thickness

(d) 0.06 times the boundary layer thickness

I have been asked this question by my college director while I was bunking the class.

My question is from Mixing Length Turbulence Model in section Turbulence Modelling of Computational Fluid Dynamics

Answer 1

The correct choice is (a) 0.09 times the boundary layer thickness

For explanation: For a turbulent boundary layer problem, the mixing length varies for different layers of the flow. For the 2-D case, the mixing length of the outer boundary layer is 0.09 times the boundary layer thickness.