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CATEGORIES:Isaac Newton Institute Seminar Series
SUMMARY:Three-dimensional stability of a horizontally shea
red flow in a stably stratified fluid - Chomaz\, J
M (LadHyX)
DTSTART;TZID=Europe/London:20081212T143000
DTEND;TZID=Europe/London:20081212T150000
UID:TALK15615AThttp://talks.cam.ac.uk
URL:http://talks.cam.ac.uk/talk/index/15615
DESCRIPTION:This work investigates the three-dimensional stabi
lity of a horizontal flow sheared horizontally\, t
he hyperbolic tangent velocity profile\, in a stab
ly stratified fluid. In an homogeneous fluid\, the
Squire theorem states that the most unstable pert
urbation is two-dimensional. When the flow is stab
ly stratified\, this theorem does not apply and we
have performed a numerical study to investigate t
he three-dimensional stability characteristics of
the flow. When the Froude number\, Fh\, is varied
from ∞ to 0.05\, the most unstable mode remains tw
o-dimensional. However\, the range of unstable ver
tical wavenumbers widens proportionally to the inv
erse of the Froude number for Fh 1. This means tha
t the stronger the stratification\, the smaller th
e vertical scales that can be destabilized. This l
oss of selectivity of the two-dimensional mode in
horizontal shear flows stratified vertically may e
xplain the layering observed numerically and exper
imentally. Extension to transient and nonlinear be
haviour are presented.
LOCATION:Seminar Room 1\, Newton Institute
CONTACT:Mustapha Amrani
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