BEGIN:VCALENDAR
VERSION:2.0
PRODID:-//Talks.cam//talks.cam.ac.uk//
X-WR-CALNAME:Talks.cam
BEGIN:VEVENT
SUMMARY:The precession resonance mechanism in nonlinear wave systems - Dan
  Lucas (DAMTP)
DTSTART:20161107T130000Z
DTEND:20161107T140000Z
UID:TALK68116@talks.cam.ac.uk
CONTACT:Doris Allen
DESCRIPTION:In this talk I will describe the theory and present numerical 
 evidence for a new type of nonlinear resonant interaction using Rossby and
  surface gravity waves as examples. The resonance constitutes a generalisa
 tion of the usual ‘exact’ resonance as we show that exchanges of energ
 y between the waves can be enhanced when the linear frequency mismatch\, o
 r detuning\, is non-zero i.e. ω1 ± ω2 ± ω3 ≠ 0. This is possible be
 cause the resonance condition is now a match between the so-called ‘prec
 ession frequency’ of a given triad interaction and an existent nonlinear
  frequency in the system. In the limit of weak nonlinearity this precessio
 n frequency is simply due to the linear ‘drift’ of the triad phase\; t
 herefore\, it tends toward the detuning. This means precession resonance o
 f this type can occur at finite amplitudes\, with nonlinear corrections co
 ntributing to the resonance. In the Rossby wave case we find precession re
 sonance leads to a collective state of synchronised oscillation\, giving e
 nhanced cascades at intermediate nonlinearity. In the water wave case we f
 ind triads can resonate\, not quartets as normal\, and we discuss ongoing 
 physical experiments in collaboration with Marc Perlin in Michigan. 
LOCATION:MR5\, Centre for Mathematical Sciences
END:VEVENT
END:VCALENDAR