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.

\[\mathrm{Mg}=-{\frac{d\sigma}{dT}}\frac{1}{\eta \alpha} \cdot L \cdot \Delta T\]

• \(\sigma\): surface tension, (SI units: N/m)
• \(L\): characteristic length, (SI units: m)
• \(\alpha\): thermal diffusivity, (SI units: m²/s)
• \(\eta\): dynamic viscosity, (SI units: kg/(s·m)),
• \(\Delta T\): temperature difference, (SI units: °C)),

See also

• Marangoni effect

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