A numerical simulation of an atmospheric vortex street



A mesoscale mixed-layer model of the planetary boundary layer is applied to the flow past a mountain island during a cold air outbreak over the Kuroshio Current. Utilizing data taken during AMTEX '75, the governing equations are integrated in time to simulate development of a Karmán vortex street downstream of the island of Cheju-do. The use of open lateral boundary conditions and an encroachment scheme which allows some mountain grid points to experience occasional encroachment of mixed-layer fluid as the mixed-layer deepens (and decroachment as the mixed layer thins) is also discussed.

Comparing various non-dimensional parameters on vortex-street characteristics, it is shown that the simulated vortex street resembles the observed atmospheric one rather well. Uncertainty in formulating the proper value of the eddy viscosity and the implication this has on Reynolds number comparisons are also discussed.