Rossby number
The Rossby number (Ro), named for Carl-Gustav Arvid Rossby, is a dimensionless number used in describing fluid flow. The Rossby number is the ratio of inertial force to Coriolis force, terms | v ⋅ ∇ v | ∼ U 2 / L {\displaystyle |\mathbf {v} \cdot \nabla \mathbf {v} |\sim U^{2}/L} and Ω × v ∼ U Ω {\displaystyle \Omega \times \mathbf {v} \sim U\Omega } in the Navier–Stokes equations respectively.