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Fluid Mechanics
Flow Through Pipes
GATE 2020
Medium

Steady, laminar, fully-developed flow of an incompressible Newtonian fluid occurs through two horizontal circular pipes I and II with the same volumetric flow rate; dII=2dI. The ratio of wall shear stress in pipe I to pipe II is

  • A0.5
  • B2
  • C4
  • 8

Explanation

For laminar pipe flow, τw=4μQ/(πR³)∝1/d³ at fixed Q. τw,I/τw,II=(dII/dI)³=2³=8.

Source: GATE CH 2020 (2020)

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