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 named after Pierre-Simon Laplace and Indonesian physicist P. C. Suratman. It is defined as follows:
L a = S u = σ ρ L μ 2 {\displaystyle \mathrm {La} =\mathrm {Su} ={\frac {\sigma \rho L}{\mu ^{2}}}}
where:
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:
L a = R e 2 W e {\displaystyle \mathrm {La} ={\frac {\mathrm {Re} ^{2}}{\mathrm {We} }}}
See also Ohnesorge number - There is an inverse relationship, L a = O h − 2 {\displaystyle \mathrm {La} =\mathrm {Oh} ^{-2}} , between the Laplace number and the Ohnesorge number.
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