Question

Normal shock waves are_______ to the local flow.

(a) Parallel

(b) Perpendicular

(c) Same

(d) Independent

The question was asked in unit test.

This is a very interesting question from Flow of Compressible Fluid through Orifices and Nozzles topic in chapter Compressible Flow of Fluid Mechanics

Answer 1

Right option is (b) Perpendicular

For explanation I would say: Normal shock waves are perpendicular to the local flow direction. The shock waves occur when the pressure builds up into an extremely thin shockwave that converts energy into heat. The waves thus take over one another.