# Rossby Number

Written by Jerry Ratzlaff on . Posted in Dimensionless Numbers

Rossby number, abbreviated as Ro, a dimensionless number, is used to describe fluid flow.  It is the ratio of internal forces to Voriolis force.

### Rossby Number Formula

$$\large{ Ro = \frac{ U }{ l \; f } }$$

Where:

$$\large{ Ro }$$ = Rossby number

$$\large{ U }$$ = characteristic velocity

$$\large{ f }$$ = Coriolis frequency

$$\large{ l }$$ = length scale of the phenomenon

Tags: Equations for Fluid