Blake number

In fluid mechanics, the Blake number is a nondimensional number showing the ratio of inertial force to viscous force. It is used in momentum transfer in general and in particular for flow of a fluid through beds of solids. It is a generalisation of the Reynolds number for flow through porous media. It is named after the US chemist Frank C. Blake (1892–1926).

Expressed mathematically the Blake number B is:

$B=\frac{u\rho D_h}{\mu (1-ϵ)}$

where

ε	=	void fraction
μ	=	dynamic viscosity
ρ	=	fluid density
Dh	=	hydraulic diameter
u	=	flow velocity