Eötvös number

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In fluid dynamics the Eötvös number (Eo) is a dimensionless number named after Hungarian physicist Loránd Eötvös (1848-1919).

Together with Morton number it can be used to characterize the shape of a fluid sphere (air bubble, water drop...). Eötvös number may be regarded as proportional to buoyancy forces divided by surface tension forces.

<math>\mathrm{Eo}=\frac{\Delta\rho \,g \,L^2}{\sigma}</math>

<math>\Delta\rho</math>: difference in density of the two phases, (SI units : kg/m³)
<math>g</math>: gravitational acceleration, (SI units : m/s²)
<math>L</math>: characteristic length, (SI units : m)
<math>\sigma</math>: surface tension, (SI units : N/m)