Question

The Prandtl number (\(N_{Pr}\)) is the ratio of

• A. Thermal diffusivity to momentum diffusivity
• B. Momentum diffusivity to mass diffusivity
• C. Momentum diffusivity to thermal diffusivity
• D. Mass diffusivity to thermal diffusivity

Hint:

Use \(N_{Pr}\) to analyze heat transfer in laminar boundary layer flows.

Answer 1

The Correct Option is C

Prandtl number is defined as:
\[ N_{Pr} = \frac{\nu}{\alpha} = \frac{\mu / \rho}{k / (\rho C_p)} = \frac{\mu C_p}{k} \]
It describes the relative thickness of velocity and thermal boundary layers.