# Laplace Number

Written by Jerry Ratzlaff on . Posted in Dimensionless Numbers

Laplace number, abbreviated as La, also called Suratman number, abbreviated as Su, are both dimensionless numbers and are used in the charcaterization of free surface fluid dynamics.  It is a ratio of surface tension to the momentum transport inside a fluid.

## formulas that use Laplace number

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

### 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 liquid