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SUMMARY:Intrusive gravity currents and the solitary wave lifecycle in a cy
 lindrical geometry - Justine McMillan (Earth &amp\; Atmospheric Sciences\,
  University of Alberta)
DTSTART:20100603T103000Z
DTEND:20100603T113000Z
UID:TALK24802@talks.cam.ac.uk
CONTACT:Catherine Pearson
DESCRIPTION:An intrusive gravity current or intrusion arises when a fluid 
 of one density propagates at an intermediate depth within a stratied ambie
 nt. Numerous experimental and theoretical studies have examined the propag
 ation of these currents in a rectilinear geometry\, however\, the dynamics
  of radially spreading\naxisymmetric intrusions is less well established. 
 By way of full-depth lock release experiments and numerical simulations\, 
 we examine the propagation of vertically symmetric intrusions in a two-lay
 er ambient in a cylindrical geometry. We show that the strong stratication
  at the interface supports the formation of a mode-2 solitary wave that su
 rrounds the intrusion head and carries it outwards at a constant speed bey
 ond six lock radii. The wave and intrusion propagate faster than a linear 
 long wave\; therefore\, there is strong evidence to support that the wave 
 is indeed nonlinear. By extending rectilinear KdV theory to allow the wave
  amplitude to decay as r^(-p) with p approximately 1/2\, we show that from
  a single measurement of wave amplitude\, the theory can be used to accura
 tely predict the amplitude\, speed and spread of the wave during its nonli
 near evolution phase.
LOCATION:Open Plan Area\, BP Institute\, Madingley Rise CB3 0EZ
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