Question

A beaker contains water up to a certain height as shown. If the water is allowed to get discharged through a small nozzle, what type of flow will it be in the pipe?

(a) steady and uniform

(b) unsteady and uniform

(c) steady and non-uniform

(d) unsteady and non-uniform

I had been asked this question during an interview.

Question is from Types of Fluid Flow in portion Kinematics of Flow and Ideal Flow of Fluid Mechanics

Answer 1

The correct answer is (d) unsteady and non-uniform

Best explanation: The velocity in which the water is discharged with a velocity  With time as the water gets discharged,v decreases as H decreases. Hence, it will be an unsteady flow.

According to the continuity equation, ρAV =constant, where ρ= density, A= cross-sectional area of flow, V = velocity of flow. In this case, water is treated as an incompressible liquid (ρ = constant) but the nozzle has a gradually decreasing diameter (A decreases). At a given instant, V at the exit of the nozzle will be more than that at it’s entrance. Hence, it will be a non-uniform flow.