# Dean Number

Written by Jerry Ratzlaff on . Posted in Dimensionless Numbers

Dean number, abbreviated De, is a dimensionless number used in momentum transfer for the flow in curved pipes and channels. The equation and calculation is shown below.

 $$\large{ De = \sqrt { \frac {d}{2r} } \frac {\rho v d}{ \mu } = \sqrt { \frac { d } { 2 r } } Re }$$ Where: $$\large{ De }$$ = Dean number $$\large{ \rho }$$  (Greek symbol rho) = density of the fluid $$\large{ d }$$ = diameter $$\large{ \mu }$$  (Greek symbol mu) = dynamic viscosity $$\large{ r }$$ = radius of curviture of the path of channel $$\large{ Re }$$ = Reynolds number $$\large{ v }$$ = axial velocity scale