Effects of weak planetary rotation on the stability and dynamics of internal stratified jets
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Authors
Radko, Timour
Lorfeld, David
Subjects
Advisors
Date of Issue
2018
Date
Publisher
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Abstract
This study explores the stability characteristics and nonlinear evolution of internal jets in rotating stratified fluids using a combination of direct numerical simulations and linear instability analyses. Our ultimate goal is the assessment of the potential impact of the Earth’s rotation on relatively small-scale structures, exemplified by turbulent wakes generated by propagating bluff objects in the ocean. We question the popular notion that ascribes a secondary role to the Coriolis effects in large Rossby number (Ro) systems. It is shown that the Earth’s rotation can substantially influence circulation patterns with Rossby numbers as high as Ro ∼ 103. Therefore, such effects must be taken into account in the numerical and theoretical models of finescale (∼10–100 m) processes in the ocean. We present a series of examples in which planetary rotation controls flows with large but finite values of Ro through centrifugal destabilization. These calculations reveal that centrifugal instabilities can affect fluid motion either directly, by modifying the basic state, or indirectly, by preferentially eliminating anticyclonic coherent vortices that form in the course of dynamic destabilization of jets. The results of this study have potentially significant geophysical implications in terms of elucidating mechanisms of energy cascade to progressively smaller scales. In the naval context, we anticipate that our investigation could influence the development of algorithms for detection and analysis of late wakes, generated by propagating submersibles in the ocean.
Type
Article
Description
The article of record as published may be found at http://dx.doi.org/10.1063/1.5049598
Series/Report No
Department
Oceanography
Organization
Naval Postgraduate School (U.S.)
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NPS Report Number
Sponsors
Naval Research Program
Funder
Naval Research Program of the Naval Postgraduate School (No. NPS-N19-N155-A).
Format
13 p.
Citation
Radko, Timour, and David Lorfeld. "Effects of weak planetary rotation on the stability and dynamics of internal stratified jets." Physics of Fluids 30.9 (2018): 096602.
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This publication is a work of the U.S. Government as defined in Title 17, United States Code, Section 101. Copyright protection is not available for this work in the United States.