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Vortex Structures in the Wake of an Idealized Seamount in Rotating, Stratified Flow
Author(s) -
Perfect B.,
Kumar N.,
Riley J. J.
Publication year - 2018
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 - 10.1029/2018gl078703
Subject(s) - seamount , vortex , barotropic fluid , eddy , strouhal number , physics , mechanics , geology , vortex shedding , stratified flow , reynolds number , stratified flows , stratification (seeds) , neutral buoyancy , buoyancy , wake , flow (mathematics) , geophysics , turbulence , oceanography , seed dormancy , germination , botany , dormancy , biology
We present the results of a 3‐D computational model of an idealized seamount in rotating, stratified flow. The emergent vortex structures in the lee of the seamount indicate that the vertical coherence of vortices is strongly dependent on the Coriolis parameter and the background buoyancy frequency. A novel finding from this work is that above a critical Burger number the vortex shedding frequency varies vertically with the local seamount diameter and adjusts such that the Strouhal number based on the local seamount diameter is consistent with high Reynolds number flow past a circular cylinder. This study extends previous literature into a regime exhibiting stronger stratification and rotation, where the transition into vertically decoupled eddies occurs. Physically, this transition is associated with the loss of geostrophy in the eddies. The mechanisms governing the transition to vertically decoupled vortices may play an important role in the energetics of a seamount interacting with a barotropic flow.