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SUMMARY:Zigzag instability of vortex arrays in stratified and rotating flu
 ids - Billant\, P (cole Polytechnique)
DTSTART:20081208T120000Z
DTEND:20081208T123000Z
UID:TALK15621@talks.cam.ac.uk
CONTACT:Mustapha Amrani
DESCRIPTION:We investigate the three-dimensional stability of columnar ver
 tical vortex arrays (Karman street\, double symmetric row of vortices) in 
 a stratified and rotating fluid by means of an asymptotic theory for long-
 vertical wavelength and well-separated vortices. It is found that both the
  Karman street and the double symmetric row are unstable to the zigzag ins
 tability when the fluid is stratified independently of the background rota
 tion. The zigzag instability bends the vortices with almost no internal de
 formation and ultimately slices the flow into horizontal layers. The resul
 ts are in excellent agreement with direct numerical stability analyses. Th
 ey may explain the formation of layers commonly observed in stratified flo
 ws.
LOCATION:Seminar Room 1\, Newton Institute
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