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Tidal Synchronization of Lee Vortices in Geophysical Wakes
Author(s) -
Puthan Pranav,
Sarkar Sutanu,
Pawlak Geno
Publication year - 2021
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2020gl090905
Subject(s) - wake , vortex , physics , vortex shedding , kármán vortex street , wake turbulence , subharmonic , mechanics , turbulence , reynolds number , nonlinear system , quantum mechanics
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 ( f s , c ) in a current without tides to the tidal frequency ( f t ), is varied to expose different regimes of tidal synchronization. When f * 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 both f t and f s , 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.