Question

In forced convection, the Nusselt number (Nu) is a function of:

• A. Re and Pr
• B. Re and Gr
• C. Pr and Gr
• D. Re and Sc

Hint:

In forced convection, the Nusselt number depends on the Reynolds number (Re) and Prandtl number (Pr) to describe the relationship between fluid flow and heat transfer.

Answer 1

The Correct Option is A

Step 1: Understanding the Nusselt number in forced convection.
In forced convection, the Nusselt number (Nu) is used to quantify the enhancement of heat transfer due to convection as compared to conduction. The Nusselt number is a function of the Reynolds number (Re), which represents the flow regime (laminar or turbulent), and the Prandtl number (Pr), which characterizes the fluid's thermal properties.

Step 2: Explanation of the options.
- (A) The Nusselt number in forced convection is indeed a function of both the Reynolds number (Re) and the Prandtl number (Pr). - (B) The Grashof number (Gr) is related to natural convection, not forced convection. - (C) The Prandtl number (Pr) and Grashof number (Gr) are involved in natural convection. - (D) The Schmidt number (Sc) is related to mass transfer, not directly to heat transfer in forced convection.

Final Answer: \[ \boxed{\text{Re and Pr}} \]