# Laplace Number

Written by Jerry Ratzlaff on . Posted in Dimensionless Numbers

Laplace number ( $$La$$ ) (also called Suratman number $$Su$$ ) (dimensionless number) is used in the charcaterization of free surface fluid dynamics.  It is a ratio of surface tension to the momentum transport inside a fluid.

### Laplace Number Formula

$$\large{ La = \frac { \sigma \rho l } { \eta^2 } }$$

Where:

$$\large{ La }$$ = Laplace number

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

$$\large{ l }$$ = length

$$\large{ \sigma }$$  (Greek symbol sigma) = surface tension

$$\large{ \eta }$$  (Greek symbol eta) = viscosity of the liquid

Tags: Equations for Fluid