Editing Froude number (section)

===Euler momentum equation===
{{see also|Euler equations (fluid dynamics)}}
Euler momentum equation is a Cauchy momentum equation with the [[Pascal law]] being the stress constitutive relation:
<math display="block">\boldsymbol \sigma = p \mathbf I </math>
in nondimensional Lagrangian form is:
<math display="block">\frac{D \mathbf u}{D t} +  \mathrm{Eu} \frac {\nabla p}{\rho}= \frac 1 {\mathrm{Fr}^2} \hat g </math>

Free Euler equations are conservative. The limit of high Froude numbers (low external field) is thus notable and can be studied with [[perturbation theory]].