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GATE 2022 AE – Question 17

Aerodynamics · Viscous flows: Hagen-Poiseuille flow, Couette flow and boundary layers · 1 mark · Multiple choice

Consider the velocity distribution, u(y) shown in the figure. For two adjacent fluid layers L1 and L2, the viscous force exerted by L1 on L2 is

source diagram and its labels are reproduced in the attached image.
  1. to the right
  2. to the left
  3. vertically upwards
  4. vertically downwards

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Correct answer: (B) to the left

Explanation

L1 moves more slowly than the adjacent lower layer L2 in the shown profile. Viscosity therefore pulls L2 backward, to the left.