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Title: Tidal Synchronization of Lee Vortices in Geophysical Wakes

Wake vortices in tidally modulated currents past a conical hill in a stratified fluid are investigated using large‐eddy‐simulation. The vortex shedding frequency is altered from its natural steady‐current value leading to synchronization of wake vortices with the tide. The relative frequency (f*), defined as the ratio of natural shedding frequency (fs,c) in a current without tides to the tidal frequency (ft), is varied to expose different regimes of tidal synchronization. Whenf*increases and approaches 0.25, vortex shedding at the body changes from a classical asymmetric Kármán vortex street. The wake evolves downstream to restore the Kármán vortex‐street asymmetry but the discrete spectral peak, associated with wake vortices, is found to differ from bothftandfs,c, a novel result. The spectral peak occurs at the first subharmonic of the tidal frequency when 0.5 ≤ f*< 1 and at the second subharmonic when 0.25 ≤ f*< 0.5.

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DOI PREFIX: 10.1029
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Journal Name:
Geophysical Research Letters
Medium: X
Sponsoring Org:
National Science Foundation
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