Blake Number

Blake number, abbreviated as Bl, a dimensionless number, used in fluid dynamics to describe the ratio of inertial force and viscous force and is used in momentum transfer and flow through beds of solids.

 

Blake Number formula
\( B \;=\; v \; \rho \; d_h \;/\; \mu \; ( 1 - \epsilon ) \)
Symbol	English	Metric
\( Bl \) = Blake Number	\(dimensionless\)	\(dimensionless\)
\( v \) = Fluid Velocity	\(ft\;/\;sec\)	\(m\;/\;s\)
\( \rho \)   (Greek symbol rho) = Fluid Density	\(lbm\;/\;ft^3\)	\(kg\;/\;m^3\)
\( d_h \) = Hydraulic Diameter	\( ft \)	\( m \)
\( \mu \)  (Greek symbol mu) = Fluid Dynamic Viscosity	\(lbf-sec\;/\;ft^2\)	\( Pa-s \)
\( \epsilon \)   (Greek symbol epsilon) = Void Fraction	\(dimensionless\)	\(dimensionless\)