The GATE Grind

GATE 2024 ME – Question 18

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

Consider incompressible laminar flow over a flat plate with freestream velocity of $u_\infty$. The Nusselt number corresponding to this flow velocity is $Nu_1$. If the freestream velocity is doubled, the Nusselt number changes to $Nu_2$. Choose the correct option for $Nu_2/Nu_1$.

  1. $\sqrt{2}$
  2. 2
  3. 1.26
  4. 1

Practise this question in The GATE Grind →

Show answer and explanation

Correct answer: (A) $\sqrt{2}$

Explanation

For laminar flow over a flat plate the Nusselt number varies as $Nu \propto Re^{1/2}Pr^{1/3}$, and the Reynolds number is proportional to the velocity. Doubling $u_\infty$ doubles $Re$, so $\frac{Nu_2}{Nu_1} = \sqrt{2}$.