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GATE 2016 ME (ME3) – Question 26

Heat Transfer · Convection: boundary layer, dimensionless parameters and correlations · 1 mark · Multiple choice

Grashof number signifies the ratio of

  1. inertia force to viscous force
  2. buoyancy force to viscous force
  3. buoyancy force to inertia force
  4. inertia force to surface tension force

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Correct answer: (B) buoyancy force to viscous force

Explanation

Gr=gβΔTL³/ν² measures the importance of buoyancy relative to viscous effects in natural convection. Its definition uses a viscous velocity scaleν/L. Thus the stated buoyancy/viscous-force interpretation is **B**; Reynolds number instead characterises imposed-flow inertia relative to viscosity.