BME Fluid Mechanics 2

Question 1

The Navier-Stokes equations describe the motion of which type of fluids?

Accepted Answer

Viscous, incompressible Newtonian fluids

Answer

The Navier-Stokes equations govern viscous, incompressible Newtonian fluid flow by relating velocity, pressure, and viscous forces.

Question 2

A fluid flows through a pipe that suddenly expands in diameter. Using the continuity equation for incompressible flow, if the diameter doubles, the velocity will:

Accepted Answer

Decrease to one-quarter

Answer

Continuity requires A₁V₁ = A₂V₂; doubling diameter quadruples area, so velocity decreases to one-quarter.

Question 3

Which dimensionless number represents the ratio of inertial forces to surface tension forces in fluid flow?

Accepted Answer

Weber number

Answer

The Weber number (We = ρV²L/σ) is the ratio of inertial to surface tension forces.

Question 4

In a laminar boundary layer over a flat plate, the boundary layer thickness δ scales with distance x from the leading edge as:

Accepted Answer

δ ∝ x^(1/2)

Answer

For laminar (Blasius) boundary layers, δ ∝ x^(1/2) based on the similarity solution.

Question 5

The head loss in a pipe due to friction (Darcy-Weisbach) is given by h_f = f(L/D)(V²/2g). If flow velocity doubles, the head loss:

Accepted Answer

Quadruples

Answer

Head loss is proportional to V², so doubling velocity quadruples the frictional head loss.

BME - Bachelor of Mechanical Engineering Practice Test

BME - Bachelor of Mechanical Engineering Practice Test

BME Fluid Mechanics 2