Question

Select the false statement for the normal shock wave.

(a) Entropy increases across normal shock wave

(b) Normal shock wave has velocity and pressure gradients

(c) Shock wave is pretty thick

(d) Thermal and frictional dissipation there

I had been asked this question in an interview for internship.

Question is taken from Flow Compressible in portion Normal Shock Waves of Aerodynamics

Answer 1

The correct choice is (c) Shock wave is pretty thick

The best I can explain: The shock waves are a very thin region and have entropy increase across them. The normal shock wave has large velocity and temperature gradients across it and hence the irreversibility. The thermal conduction and frictional effect lead to increase in entropy.