Fluid Mechanics

311.In the low Reynolds number region, the drag force on a sphere is proportional to

  1. V
  2. v2
  3. V4
  4. V0.5
Correct answer: (A)
V

312.In the Newton's law range, the terminal velocity of a solid spherical particle falling through a stationary fluid mass is _________ the fluid viscosity.

  1. Directly proportional to
  2. Inversely proportional to
  3. Inversely proportional to the square root of
  4. Independent of
Correct answer: (B)
Inversely proportional to

313.In turbulent flow, a rough pipe has the same friction factor as a smooth pipe

  1. In the zone of complete turbulence
  2. When the roughness projections are much smaller than the thickness of the laminar film
  3. Everywhere in the transition zone
  4. When the friction factor is independent of the Reynold's number
Correct answer: (B)
When the roughness projections are much smaller than the thickness of the laminar film

314.In turbulent flow, the

  1. Fluid particles move in an orderly manner
  2. Momentum transfer is on molecular scale only
  3. Shear stress is caused more effectively by cohesion than momentum transfer
  4. Shear stresses are generally larger than in a similar laminar flow
Correct answer: (D)
Shear stresses are generally larger than in a similar laminar flow

315.In which of the following body shapes, the pressure drag is large compared to the friction drag?

  1. Stream line body
  2. Two dimensional body
  3. Bluff body
  4. None of these
Correct answer: (C)
Bluff body

316.In which of the following cases, it is possible for flow to occur from low pressure to high pressure?

  1. Flow of liquid upward in a vertical pipe
  2. Flow through a converging section
  3. Flow of air downward in a pipe
  4. Impossible in a constant cross-section conduit
Correct answer: (B)
Flow through a converging section

317.In which type of fluid flow, the velocity of flow of fluid changes from point to point in the fluid at any instant?

  1. Rotational
  2. Unsteady
  3. Turbulent
  4. Non-uniform
Correct answer: (D)
Non-uniform

318.Interstage coolers are provided in a multistage compressor to

  1. Save power in compressing a given volume to a given pressure
  2. Cool the delivered air
  3. Achieve the exact delivery pressure
  4. None of these
Correct answer: (A)
Save power in compressing a given volume to a given pressure

319.Isothermal turbulent flow of a fluid results in decrease of its pressure, which depends on the

  1. Wall roughness
  2. Reynolds number
  3. Both (A) & (B)
  4. Neither (A) nor (B)
Correct answer: (C)
Both (A) & (B)

320.Isotropic turbulence occurs

  1. Where there is no velocity gradient
  2. At higher temperatures
  3. Only in Newtonian fluids
  4. None of these
Correct answer: (A)
Where there is no velocity gradient
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