| Popis: |
In geophysical flows, vortices are present at very different scales. Examples of them are the meddies, formed at the outlet of the Mediterranean Sea or the vorticity dipoles, occurring when water flushes from a channel into the open sea. In this paper we investigate the formation and the evolution of a spanwise vortex in the latter system, when a periodic forcing is imposed. To this end the Navier-Stokes and continuity equations are solved with a finite volume code (OpenFOAM 2008). The numerical solution has been obtained for a Reynolds number \(Re = 1{,}000\) and a Strouhal number \(S = 0.02\). For comparison, we carried a simulation in a flow produced by a single pulse. We have found that the spanwise vortex appears in front of the dipole. It detaches from the bottom and moves away. When flow is produced by a pulse, this vortex has a horseshoe shape, while for a periodic forcing flow, the shape of the spanwise vortex evolves in time. |
