W. Rockwell Geyer
Richard P. Signell
1991
<div class="t m0 x4 h5 y4 ff1 fs4 fc0 sc0 ls0 ws0"><span class="current-selection">Eddies </span><span class="current-selection">with </span><span class="current-selection">length </span><span class="current-selection">scales </span><span class="current-selection">of </span><span class="current-selection">1-10 </span><span class="current-selection">km </span><span class="current-selection">are </span><span class="current-selection">commonly </span><span class="current-selection">observed </span><span class="current-selection">in </span><span class="current-selection">coastal </span><span class="current-selection">waters </span><span class="current-selection">and </span><span class="current-selection">play </span><span class="current-selection">an </span><span class="current-selection">important </span><span class="current-selection">role </span><span class="current-selection">in </span><span class="current-selection">the </span><span class="current-selection">dispersion </span><span class="current-selection">of </span><span class="current-selection">water-borne </span><span class="current-selection">materials. </span><span class="current-selection">The </span><span class="current-selection">generation </span><span class="current-selection">and </span><span class="current-selection">evolution </span><span class="current-selection">of </span><span class="current-selection">these </span><span class="current-selection">eddies </span><span class="current-selection">by </span><span class="current-selection">oscillatory </span><span class="current-selection">tidal </span><span class="current-selection">flow </span><span class="current-selection">around </span><span class="current-selection">coastal </span><span class="current-selection">headlands </span><span class="current-selection">is </span><span class="current-selection">investigated </span><span class="current-selection">with </span><span class="current-selection">analytical </span><span class="current-selection">and </span><span class="current-selection">nu</span><span class="current-selection">merical </span><span class="current-selection">models. </span><span class="current-selection">Using </span><span class="current-selection">shallow </span><span class="current-selection">water </span><span class="current-selection">depth-averaged </span><span class="current-selection">vorticity </span><span class="current-selection">dynamics, </span><span class="current-selection">eddies </span><span class="current-selection">are </span><span class="current-selection">shown </span><span class="current-selection">to </span><span class="current-selection">form </span><span class="current-selection">when </span><span class="current-selection">flow </span><span class="current-selection">separation </span><span class="current-selection">occurs </span><span class="current-selection">near </span><span class="current-selection">the </span><span class="current-selection">tip </span><span class="current-selection">of </span><span class="current-selection">the </span><span class="current-selection">headland, </span><span class="current-selection">causing </span><span class="current-selection">intense </span><span class="current-selection">vorticity </span><span class="current-selection">generated </span><span class="current-selection">along </span><span class="current-selection">the </span><span class="current-selection">headland </span><span class="current-selection">to </span><span class="current-selection">be </span><span class="current-selection">injected </span><span class="current-selection">into </span><span class="current-selection">the </span><span class="current-selection">interior. </span><span class="current-selection">An </span><span class="current-selection">analytic </span><span class="current-selection">boundary </span><span class="current-selection">layer </span><span class="current-selection">model </span><span class="current-selection">demonstrates </span><span class="current-selection">that </span><span class="current-selection">flow </span><span class="current-selection">separation </span><span class="current-selection">occurs </span><span class="current-selection">when </span><span class="current-selection">the </span><span class="current-selection">pressure </span><span class="current-selection">gradient </span><span class="current-selection">along </span><span class="current-selection">the </span><span class="current-selection">boundary </span><span class="current-selection">switches </span><span class="current-selection">from </span><span class="current-selection">favoring </span><span class="current-selection">(ac</span><span class="current-selection">celerating) </span><span class="current-selection">to </span><span class="current-selection">adverse </span><span class="current-selection">(decelerating), </span><span class="current-selection">and </span><span class="current-selection">its </span><span class="current-selection">occurrence </span><span class="current-selection">depends </span><span class="current-selection">principally </span><span class="current-selection">on </span><span class="current-selection">three </span><span class="current-selection">parameters: </span><span class="current-selection">the </span><span class="current-selection">aspect </span><span class="current-selection">ratio </span><span class="current-selection">[b/a], </span><span class="current-selection">where </span><span class="current-selection">b </span><span class="current-selection">and </span><span class="current-selection">a </span><span class="current-selection">are </span><span class="current-selection">characteristic </span><span class="current-selection">width </span><span class="current-selection">and </span><span class="current-selection">length </span><span class="current-selection">scales </span><span class="current-selection">of </span><span class="current-selection">the </span><span class="current-selection">headland; </span><span class="current-selection">[H/CDa], </span><span class="current-selection">where </span><span class="current-selection">H is </span><span class="current-selection">the </span><span class="current-selection">water </span><span class="current-selection">depth, </span><span class="current-selection">CD </span><span class="current-selection">is </span><span class="current-selection">the </span><span class="current-selection">depth-averaged </span><span class="current-selection">drag </span><span class="current-selection">coefficient; </span><span class="current-selection">and </span><span class="current-selection">[Uo/aa], </span><span class="current-selection">where </span><span class="current-selection">Uo </span><span class="current-selection">and </span><span class="current-selection">a </span><span class="current-selection">are </span><span class="current-selection">the </span><span class="current-selection">magnitude </span><span class="current-selection">and </span><span class="current-selection">frequency </span><span class="current-selection">of </span><span class="current-selection">the </span><span class="current-selection">far-field </span><span class="current-selection">tidal </span><span class="current-selection">flow. </span><span class="current-selection">Simulations </span><span class="current-selection">with </span><span class="current-selection">a </span><span class="current-selection">depth-averaged </span><span class="current-selection">numerical </span><span class="current-selection">model </span><span class="current-selection">show </span><span class="current-selection">a </span><span class="current-selection">wide </span><span class="current-selection">range </span><span class="current-selection">of </span><span class="current-selection">responses </span><span class="current-selection">to </span><span class="current-selection">changes </span><span class="current-selection">in </span><span class="current-selection">these </span><span class="current-selection">parameters, </span><span class="current-selection">including </span><span class="current-selection">cases </span><span class="current-selection">where </span><span class="current-selection">no </span><span class="current-selection">separation </span><span class="current-selection">occurs, </span><span class="current-selection">cases </span><span class="current-selection">where </span><span class="current-selection">only </span><span class="current-selection">one </span><span class="current-selection">eddy </span><span class="current-selection">exists </span><span class="current-selection">at </span><span class="current-selection">a </span><span class="current-selection">given </span><span class="current-selection">time, </span><span class="current-selection">and </span><span class="current-selection">cases </span><span class="current-selection">where </span><span class="current-selection">bottom </span><span class="current-selection">friction </span><span class="current-selection">is </span><span class="current-selection">weak </span><span class="current-selection">enough </span><span class="current-selection">that </span><span class="current-selection">eddies </span><span class="current-selection">produced </span><span class="current-selection">during </span><span class="current-selection">successive </span><span class="current-selection">tidal cycles </span><span class="current-selection">coexist, </span><span class="current-selection">interacting </span><span class="current-selection">strongly </span><span class="current-selection">with </span><span class="current-selection">each </span><span class="current-selection">other. </span><span class="current-selection">These </span><span class="current-selection">simulations </span><span class="current-selection">also </span><span class="current-selection">demonstrate </span><span class="current-selection">that </span><span class="current-selection">in </span><span class="current-selection">unsteady </span><span class="current-selection">flow, </span><span class="current-selection">a </span><span class="current-selection">strong </span><span class="current-selection">start-up </span><span class="current-selection">vortex </span><span class="current-selection">forms </span><span class="current-selection">after </span><span class="current-selection">the </span><span class="current-selection">flow </span><span class="current-selection">separates, </span><span class="current-selection">leading </span><span class="current-selection">to </span><span class="current-selection">a </span><span class="current-selection">much </span><span class="current-selection">more </span><span class="current-selection">intense </span><span class="current-selection">patch </span><span class="current-selection">of </span><span class="current-selection">vorticity </span><span class="current-selection">and </span><span class="current-selection">stronger </span><span class="current-selection">recirculation </span><span class="current-selection">than </span><span class="current-selection">found </span><span class="current-selection">in </span><span class="current-selection">steady </span><span class="current-selection">flow. </span></div>
application/pdf
10.1029/90JC02029
en
American Geophysical Union
Transient eddy formation around headlands
article