Question

Vortical singularity exists at which part of the conical surface?

(a) Leeward surface

(b) Windward surface

(c) Axis of the cone

(d) Vertex of the cone

The question was asked in an interview for internship.

My question is from Cones at Angle of Attack topic in portion Three-Dimensional Flow of Aerodynamics

Answer 1

Right option is (b) Windward surface

For explanation: When a cone is at an angle of attack, the windward streamline is at ϕ = 0 deg and the leeward streamline is at ϕ = 180 deg. The flow through leeward streamline acquires an entropy of s1 which curves toward the windward surface thus wetting the entire cone. The flow through windward surface has an entropy of s2 as well as entropy s1 from the streamlines that curve upward to the windward side. This leads to the windward portion of the cone with two values of entropy which is known as a vortical singularity.