Question

The rate of dissipation of kinematic eddy viscosity parameter is Cw1ρ\((\frac{\tilde{ν}}{κy})^2 f_w\). What is the length scale used here?

(a) κy

(b) (κy)^2

(c) \(\frac{C_{w1}}{y}\)

(d) \(\frac{y}{C_{w1}} \)

This question was posed to me by my school principal while I was bunking the class.

The doubt is from Turbulence Modelling topic in chapter Turbulence Modelling of Computational Fluid Dynamics

Answer 1

The correct choice is (a) κy

To elaborate: The length scale cannot be computed in the Spalart-Allmaras model. It must be specified separately. The length scale used here is κy. Where, κ is the von Karman’s constant which is equal to 0.4187 and y is the distance from the wall.