Question

The velocity at cross-stream of a turbulent wake is calculated using the formula

\(\frac{U_{max}-U}{U_{max}-U_{min}}=b(\frac{y}{b})\)

Note:

U_max→ Maximum velocity at a particular cross-section

U_min→ Minimum velocity at a particular cross-section

y → Distance in the cross-stream direction from the centre line at the cross section

b → Cross-stream half width

U → Velocity at the distance ‘y’

The minimum velocity here corresponds to _____________

(a) Velocities at the edges

(b) Velocities just downstream of the object

(c) Velocities of the surrounding free stream

(d) Velocities at the centreline

This question was posed to me in an internship interview.

I'm obligated to ask this question of Free and Wall Turbulence in division Turbulence Modelling of Computational Fluid Dynamics

Answer 1

Right choice is (b) Velocities just downstream of the object

Explanation: \(\frac{U_{max}-U}{U_{max}-U_{min}}=b(\frac{y}{b})\) is the formula used to calculate the velocity at a distance from the centre-line in the cross-stream direction. The minimum velocities here corresponds to the starting of the wake, which is just downstream of the object.