Question

The dimensional number associated with mass transfer is
1. Schmidt Number
2. Nusselt Number
3. Biot Number
4. Mach Number

Answer 1

Correct Answer - Option 1 : Schmidt Number

Concept:

Schmidt number is a dimensionless number and defined as the ratio between momentum diffusivity and mass diffusivity, and is used to characterize the fluid flows where both momentum and mass transfer are involved.

It is given by 

\(Schmidt\;number\;\left( {Sc} \right) = \frac{{Momentum\;diffusivity}}{{Mass\;diffusivity}} = \frac{{\nu \;\left( {kinematic\;viscosity} \right)}}{{D\;\left( {mass\;diffusivity} \right)}}\)

For higher Schmidt numbers, momentum diffusion dominates, and for lower Schmidt numbers, mass diffusion dominates

Schmidt number can be considered analogous to Prandtl number, while the

Prandtl number describes the diffusion of heat (thermal boundary layer).

Schmidt number describes the diffusion of mass (concentration boundary layer).