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Title: High Drag States in Tidally Modulated Stratified Wakes
Abstract Large-eddy simulations (LES) are employed to investigate the role of time-varying currents on the form drag and vortex dynamics of submerged 3D topography in a stratified rotating environment. The current is of the form U c + U t sin(2 πf t t ), where U c is the mean, U t is the tidal component, and f t is its frequency. A conical obstacle is considered in the regime of low Froude number. When tides are absent, eddies are shed at the natural shedding frequency f s , c . The relative frequency is varied in a parametric study, which reveals states of high time-averaged form drag coefficient. There is a twofold amplification of the form drag coefficient relative to the no-tide ( U t = 0) case when lies between 0.5 and 1. The spatial organization of the near-wake vortices in the high drag states is different from a Kármán vortex street. For instance, the vortex shedding from the obstacle is symmetric when and strongly asymmetric when . The increase in form drag with increasing stems from bottom intensification of the pressure in the obstacle lee which we link to changes in flow separation and near-wake vortices.  more » « less
Award ID(s):
1737367
NSF-PAR ID:
10330717
Author(s) / Creator(s):
; ;
Date Published:
Journal Name:
Journal of Physical Oceanography
Volume:
52
Issue:
6
ISSN:
0022-3670
Page Range / eLocation ID:
1033 to 1048
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
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