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GATE 2021 ME (ME2) – Question 20

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

In forced convective heat transfer, Stanton number (St), Nusselt number (Nu), Reynolds number (Re) and Prandtl number (Pr) are related as

  1. $St=Nu/(RePr)$
  2. $St=NuPr/Re$
  3. $St=NuPrRe$
  4. $St=NuRe/Pr$

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Show answer and explanation

Correct answer: (A) $St=Nu/(RePr)$

Explanation

Use $Nu=hL/k$, $Re=\rho UL/\mu$ and $Pr=\mu c_p/k$. Their product RePr is ρULcₚ/k.

Therefore $Nu/(RePr)=h/(\rho Uc_p)=St$. **Answer: A**.