Bejan number

Etymology
Named after.

Noun

 * 1)  A dimensionless number: the ratio of heat transfer irreversibility to total irreversibility due to heat transfer and fluid friction: $$\mathrm{Be} = \frac{\dot S'_{\mathrm{gen},\, \Delta T}}{\dot S'_{\mathrm{gen},\, \Delta T}+ \dot S'_{\mathrm{gen},\, \Delta p}}$$, where $$\dot S'_{\mathrm{gen},\, \Delta T}$$ is the entropy generation contributed by heat transfer and $$\dot S'_{\mathrm{gen},\, \Delta p}$$ is the entropy generation contributed by fluid friction.
 * 2)  A dimensionless number: the pressure drop along the fluid path length in both external flows and internal flows: $$\mathrm{Be_L} = \frac{\Delta p \, L^2} {\mu \nu}$$, where $$\mu$$ is the dynamic viscosity, $$\nu$$ is the momentum diffusivity (or Kinematic viscosity) and $$L$$ is fluid path length.