Lewis Number

Written by Jerry Ratzlaff on . Posted in Dimensionless Numbers

Lewis number, abbreviated 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.


Lewis Number formula

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


\(\large{ Le }\) = 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