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SUMMARY:Inertia-gravity-wave generation: a geometric-optics approach - Van
 neste\, J (Edinburgh)
DTSTART:20081210T100000Z
DTEND:20081210T103000Z
UID:TALK15606@talks.cam.ac.uk
CONTACT:Mustapha Amrani
DESCRIPTION:The generation of inertia-gravity waves in complex flows is ex
 amined using a geometric-optics approach. This approach considers the dyna
 mics of a small-scale wavepacket in prescribed time-dependent\, balanced f
 low. The wavepacket is assumed to be in the so called wave-capture regime\
 , where the wave intrinsic frequency is negligible compared with the Doppl
 er shift. The dynamics is reduced to a number of ordinary differential equ
 ations describing the evolution of the wavepacket position\, of the waveve
 ctor\, and of three scalar fields describing the wavepacket amplitude and 
 polarisation. The approach clearly identifies two classes of wave-generati
 on processes: unbalanced instabilities\, associated with linear interactio
 ns between inertia-gravity waves\, and spontaneous generation\, associated
  with a conversion between vortical and inertia-gravity modes. Application
 s to idealised and realistic flows are discussed.
LOCATION:Seminar Room 1\, Newton Institute
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