# Marangoni number

The Marangoni number (Mg) is a dimensionless number named after Italian scientist Carlo Marangoni. The Marangoni number may be regarded as proportional to (thermal-) surface tension forces divided by viscous forces. It is – for example – applicable to bubble and foam research or calculations of cryogenic spacecraft propellant behaviour.

$\mathrm{Mg} = - {\frac{d\sigma}{dT}}\frac{L \Delta T}{\eta \alpha}$