# Dean Number

Written by Jerry Ratzlaff on . Posted in Dimensionless Numbers

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

## Formulas that use Dean number

 $$\large{ De = \sqrt { \frac {d}{2 \; r} } \; \frac {\rho \; v \; d}{ \mu } = \sqrt { \frac { d } { 2 \; r } } \; Re }$$

### Where:

$$\large{ De }$$ = Dean number

$$\large{ \rho }$$  (Greek symbol rho) = density of 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