Question

With the boundary layer separation, displacement thickness________

(a) Increases

(b) Decreases

(c) Remains Same

(d) Independent

I have been asked this question in exam.

This intriguing question comes from Separation of Boundary Layer in division Boundary Layer Flow & Forces on Sub-merged Bodies of Fluid Mechanics

Answer 1

Right answer is (a) Increases

For explanation I would say: With the boundary layer separation, displacement thickness increases sharply. This helps to modify the outside potential flow and its pressure field. Thus, option ‘a’ is the correct choice.