Marangoni number

The Marangoni number (Ma) 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{Ma} = - {\frac{d\gamma}{dT}}\frac{L \Delta T}{\eta \alpha}

γ: surface tension, (SI units: N/m);
L: characteristic length, (SI units: m);
$\alpha$ : thermal diffusivity, (SI units: m²/s);
η: dynamic viscosity, (SI units: kg/(s·m));
∆T: temperature difference, (SI units: K).

Marangoni number

See also