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:

\[La = Su = \frac{\sigma \rho L}{\mu^2}\,\]

where:

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

\[La = \frac{Re^2}{We}\,\]

See also

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