# Froude Number

Written by Jerry Ratzlaff on . Posted in Dimensionless Numbers

## Froude Number

Froude number ( $$Fr$$ ) (dimensionless number) is the ratio of inertial force to gravitational force. It is used for wave and surface behavior for mixed natural and forced convection.

### Froude Number FORMULA

$$Fr = \frac { V } { \sqrt { g \; h_m } }$$          $$Froude \; number \;=\; \frac { velocity } { \sqrt { gravitational \; acceleration \;\;x\;\; mean \; depth } }$$

Where:

$$Fr$$ = Froude number

$$V$$ = flow velocity

$$g$$ = gravitational acceleration

$$h_m$$ = mean depth

Solve for:

$$V = Fr \sqrt { g \; h_m }$$

$$g = \frac {V^2} { h_m \; {Fr}^2 }$$

$$h_m = \frac {V^2} { g \; {Fr}^2 }$$