Damping mechanisms of internal waves in continuously stratified rotating basins

K. Shimizu, Jorg Imberger

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Abstract

Damping mechanisms, damping rates and the dissipative modal structure of internalwaves in stratified rotating circular basins are investigated analytically. The dampingis shown to be due to a combination of the internal-wave cancelling, where wavesemitted by the oscillatory boundary layers destructively interact with the parent waveand drain energy from it, and spin-down modified by the periodicity, where the energyis drained by the sinks and sources at the bottom corner caused by a discontinuity inthe Ekman transport. It is shown that super-inertial Poincar´e waves and sub-inertialKelvin waves are damped predominantly by the internal-wave cancelling and modifiedspin-down, respectively. These processes also modify the internal-wave structure; forsuper-inertial waves, the boundary-layer-generated waves intensify the interior flowin the lower part of the water column and delay the phase relative to the isopycnaldisplacements, but for sub-inertial waves, the Ekman pumping and the corner sinksand sources add a horizontal circular flow that slants the crest and trough backwardsnear the wall.
Original languageEnglish
Pages (from-to)137-172
JournalJournal of Fluid Mechanics
Volume637
DOIs
Publication statusPublished - 2009

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