Quantifying the impacts of the angle of attack on the morphology of
atmospheric von Kármán vortex stree
Abstract
A mesoscale model is used to systematically
investigate how the incoming flow incidence angle affects the
development of atmospheric von Kármán vortex streets for
non-axisymmetric islands. The analysis is focused on an event observed
on the leeward side of Guadalupe Island. By keeping the synoptic
conditions the same, several simulations are performed for rotated
orientations of the island topography, which correspond to a change in
the angle of attack relative to the upstream flow. The asymmetry of the
vortex shedding and the role of the leading and trailing edge are in
line with what was observed in laboratory von Kármán vortex streets past
a flat plate. The eddies become larger with increasing angle of attack
while the shedding frequency decreases, and the asymmetry between
cyclonic and anticyclonic eddies weakens. Cyclonic vortices are more
developed and stronger under typical conditions when they are shed from
the trailing edge. However, the asymmetry favors anticyclonic vortices
when the cyclonic vortices are shed from the leading edge.