The Laplace number (La), also known as the Suratman number (Su), is a dimensionless number used in the characterization of free surface fluid dynamics. It represents a ratio of surface tension to the momentum-transport (especially dissipation) inside a fluid.

It is defined as follows:

\( {\mathrm {La}}={\mathrm {Su}}={\frac {\sigma \rho L}{\mu ^{2}}} \)


σ = surface tension
ρ = density
L = length
μ = liquid viscosity

Laplace number is related to Reynolds number (Re) and Weber number (We) in the following way:

\( {\mathrm {La}}={\frac {{\mathrm {Re}}^{2}}{{\mathrm {We}}}} \)

See also

Ohnesorge number - There is an inverse relationship, \( {\mathrm {La}}={\mathrm {Oh}}^{{-2}} \), between the Laplace number and the Ohnesorge number.

Dimensionless numbers in fluid mechanics

Archimedes Atwood Bagnold Bejan Biot Bond Brinkman Capillary Cauchy Chandrasekhar Damköhler Darcy Dean Deborah Dukhin Eckert Ekman Eötvös Euler Froude Galilei Graetz Grashof Görtler Hagen Iribarren Kapitza Keulegan–Carpenter Knudsen Laplace Lewis Mach Marangoni Morton Nusselt Ohnesorge Péclet Prandtl
magnetic turbulent Rayleigh Reynolds
magnetic Richardson Roshko Rossby Rouse Schmidt Scruton Sherwood Shields Stanton Stokes Strouhal Stuart Suratman Taylor Ursell Weber Weissenberg Womersley

Physics Encyclopedia



Hellenica World - Scientific Library

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