# Bejan Number - Fluid Mechanics

Written by Jerry Ratzlaff on . Posted in Dimensionless Numbers

Bejan number - fluid mechanics, abbreviated as Be, a dimensionless number, is the pressure drop along a length of channel.

## Bejan Number - Fluid Transfer formula

$$\large{ Be = \frac{ \Delta p \; l^2 }{ \mu \; \nu } }$$
Symbol English Metric
$$\large{ Be }$$ = Bejan number $$\large{dimensionless}$$
$$\large{ l }$$ = length of channel $$\large{ft}$$ $$\large{m}$$
$$\large{ \mu }$$  (Greek symbol mu) = dynamic viscosity $$\large{\frac{lbf-sec}{ft^2}}$$ $$\large{ Pa-s }$$
$$\large{ \nu }$$  (Greek symbol nu) = momentum diffusivity (kinematic viscosity) $$\large{\frac{ft^2}{sec}}$$ $$\large{\frac{m^2}{s}}$$
$$\large{ \Delta p }$$ = pressure drop $$\large{\frac{lbf}{in^2}}$$ $$\large{Pa}$$