Topic: Heat Transfer
The Lewis number which is a measure of relative thermal and concentration boundary layer thicknesses is defined as, (Re: Reynold's number, Pr: Prandtl number, Sc: Schmidt number)
- A. $Re\times Pr$
- B. $Sc/Pr$
- C. $Re/Sc$
- D. $Sc\times Pr$
Answer: B. $Sc/Pr$
Explanation: Lewis number is defined as the ratio of thermal diffusivity to mass diffusivity, which is mathematically equivalent to the ratio of Schmidt number to Prandtl number ($Le = Sc/Pr$).