Physics:Laplace number

Short description: Dimensionless parameter in fluid mechanics

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:

$\mathrm{L}\mathrm{a}=\mathrm{S}\mathrm{u}=\frac{\sigma \rho L}{{\mu }^2}$

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:

$\mathrm{L}\mathrm{a}=\frac{{\mathrm{R}\mathrm{e}}^2}{\mathrm{W}\mathrm{e}}$

See also

• Ohnesorge number - There is an inverse relationship, $\mathrm{L}\mathrm{a}={\mathrm{O}\mathrm{h}}^{-2}$, between the Laplace number and the Ohnesorge number.