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GATE 2023 ME – Question 21

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

Consider incompressible laminar flow of a constant property Newtonian fluid in an isothermal circular tube. The flow is steady with fully-developed temperature and velocity profiles. The Nusselt number for this flow depends on

  1. neither the Reynolds number nor the Prandtl number
  2. both the Reynolds and Prandtl numbers
  3. the Reynolds number but not the Prandtl number
  4. the Prandtl number but not the Reynolds number

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Correct answer: (A) neither the Reynolds number nor the Prandtl number

Explanation

For fully developed laminar flow in a circular tube with a uniform wall temperature, the Nusselt number is a constant, $Nu = 3.66$. It does not depend on the Reynolds or the Prandtl number.