Test: Flow Through Pipes - 1 - Mechanical Engineering MCQ

For one-dimensional fully developed viscous flow between two fixed parallel plates (plane Poiseuille flow), the velocity profile is parabolic. The maximum velocity umaxu_{max}umax​ occurs at the centre of the channel

option A is correct

• The head loss in a sudden contraction is calculated using the formula:
  Head Loss = (1 - C_c)² * (V₂² - V₁²)/2g

Given:

• Initial velocity head, V₁²/2g = 0.5 m
• Final velocity head, V₂²/2g = 1.25 m
• C_c = 0.66
• Substitute values:
  Head Loss = (1 - 0.66)² * (1.25 - 0.5) = 0.332 m
• The correct answer is B: 0.332 m.

In sudden contraction, right after the sudden contraction  Ac , a vena contracta is formed; and then, right after, the flow widens again to fill the entire pipe. The region between the wall interior pipe and the vena contracta will be a region of separated flow.  The flow pattern after the vena contracta is similar to that after an abrupt enlargement and the loss is caused due to expansion of flow after sudden contraction.

Head loss for well rounded entrance as compared to sharp cornered entrance is very small.

For given condition,