BME Fluid Mechanics 4

Question 1

Cavitation in hydraulic machinery occurs when the local fluid pressure drops below the:

Accepted Answer

Vapor pressure of the fluid

Answer

Cavitation occurs when local static pressure falls below the fluid's vapor pressure, causing vapor bubble formation.

Question 2

For compressible flow in a converging-diverging nozzle, a normal shock wave can appear in the:

Accepted Answer

Diverging section at supersonic conditions

Answer

Normal shocks form in the diverging section when back pressure is between the design (fully supersonic) and subsonic exit conditions.

Question 3

The concept of 'fully developed flow' in a pipe means that:

Accepted Answer

The velocity profile no longer changes with downstream distance

Answer

Fully developed flow means the velocity profile shape is constant with axial position; only pressure continues to drop linearly.

Question 4

The vorticity vector ω in a fluid flow field is defined as:

Accepted Answer

ω = ∇×V (curl of velocity)

Answer

Vorticity is ω = ∇×V, representing the local angular rotation rate of a fluid element.

Question 5

Stokes' Law for the drag force on a slowly moving sphere in a viscous fluid is:

Accepted Answer

F_D = 3πμVD

Answer

For creeping (Stokes) flow (Re ≪ 1), the drag on a sphere is F_D = 3πμVD where D is diameter.

BME - Bachelor of Mechanical Engineering Practice Test