# Froude Number

on . Posted in Dimensionless Numbers

Froude number, abbreviated as Fr, a 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

$$\large{ Fr = \frac{ v }{ \sqrt { g \; h_m } } }$$
Symbol English Metric
$$\large{ Fr }$$ = Froude number $$\large{dimensionless}$$
$$\large{ g }$$ = gravitational acceleration $$\large{ \frac{ft}{sec^2}}$$ $$\large{ \frac{m}{s^2}}$$
$$\large{ h_m }$$ = mean depth $$\large{ft}$$ $$\large{m}$$
$$\large{ v }$$ = velocity of flow $$\large{ \frac{ft}{sec}}$$ $$\large{ \frac{m}{s}}$$