Question

Oblique shock waves are ______ to the local flow.

(a) Parallel

(b) Perpendicular

(c) Less than 90 degrees

(d) Independent

This question was posed to me by my college professor while I was bunking the class.

Origin of the question is Flow of Compressible Fluid through Orifices and Nozzles in chapter Compressible Flow of Fluid Mechanics

Answer 1

The correct choice is (a) Parallel

Explanation: Oblique shock waves have an angle less than 90 degrees with respect to its local flow. They are similar to the normal shock waves. When there is any disturbance to the fluid flow at a non-zero angle oblique shock is formed.