Convective heat transfer correlations: The ratio of the Nusselt number to the product of Reynolds number and Prandtl number equals which dimensionless group?

Introduction / Context:
Dimensionless numbers simplify heat transfer analysis by grouping variables. Relating Nusselt (Nu), Reynolds (Re), and Prandtl (Pr) numbers helps compare convection problems across scales.

Given Data / Assumptions:

• Nusselt number: Nu = h * L / k.
• Reynolds number: Re = ρ * V * L / μ.
• Prandtl number: Pr = μ * c_p / k.
• Steady convection, characteristic length L, properties evaluated at film temperature.

Concept / Approach:
The Stanton number, St, is defined as St = h / (ρ * V * c_p). Algebra shows St = Nu / (Re * Pr). Recognizing this identity clarifies how convective heat transfer coefficient relates to flow inertia and thermal diffusivity.

Step-by-Step Solution:

Verification / Alternative check:
Check dimensions: all groups are dimensionless; the identity holds for any consistent unit system.

Why Other Options Are Wrong:

• Biot number compares internal conduction to surface convection, unrelated to Re or Pr directly.
• Peclet number is Re * Pr, not the ratio in question.
• Grashof number governs natural convection, independent of Re for forced convection.

Common Pitfalls:
Confusing Peclet and Stanton numbers; remember St = Nu/(RePr).

Final Answer:
Stanton number