Question

“The velocity of entrance and exit through a nozzle remains the same.” Is this ever possible?

(a) only if the flow is compressible

(b) only if the flow is laminar

(c) only if the flow is rotational

(d) never possible

This question was addressed to me during an interview for a job.

This question is from Types of Fluid Flow topic in division Kinematics of Flow and Ideal Flow of Fluid Mechanics

Answer 1

Right option is (a) only if the flow is compressible

To explain I would say: According to the continuity equation, ρAV =constant, where ρ= density, A= cross sectional area of flow, V = velocity of flow. If v =constant, ρA =constant. Thus a change is A will mean a change in ρ. Hence, the flow is possible only if the fluid is compressible.