Intrusive gravity currents and the solitary wave lifecycle in a cylindrical geometry

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• Justine McMillan (Earth & Atmospheric Sciences, University of Alberta)
• Thursday 03 June 2010, 11:30-12:30
• Open Plan Area, BP Institute, Madingley Rise CB3 0EZ.

If you have a question about this talk, please contact Catherine Pearson.

An intrusive gravity current or intrusion arises when a fluid of one density propagates at an intermediate depth within a stratied ambient. Numerous experimental and theoretical studies have examined the propagation of these currents in a rectilinear geometry, however, the dynamics of radially spreading axisymmetric 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-layer ambient in a cylindrical geometry. We show that the strong stratication at the interface supports the formation of a mode-2 solitary wave that surrounds the intrusion head and carries it outwards at a constant speed beyond 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 accurately predict the amplitude, speed and spread of the wave during its nonlinear evolution phase.

This talk is part of the Institute for Energy and Environmental Flows (IEEF) series.

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• Open Plan Area, BP Institute, Madingley Rise CB3 0EZ
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