Lewis Number

Written by Jerry Ratzlaff on . Posted in Dimensionless Numbers

Lewis number, abbreviated as Le, is a dimensionless number which is the ratio of thermal diffusivity to mass diffusivity. It is used to characterize fluid flows where there is simultaneous heat and mass transfer.

\(\large{ Le = \frac{  \alpha }{ D_m }   }\)         

Where:

\(\large{ Le }\) = Lewis number

\(\large{ D_m }\) = mass diffusivity

\(\large{ \alpha }\)  (Greek symbol alpha) = thermal diffusivity

Solve for:

\(\large{ \alpha = Le \; D_m  }\)

\(\large{ D_m = \frac{  \alpha }{ Le }  }\)

Tags: Equations for Temperature Equations for Mass