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Nonlinear Physics Seminar: "Quasi 2D and wave turbulence in rotating flows" | The Racah Institute of Physics

Nonlinear Physics Seminar: "Quasi 2D and wave turbulence in rotating flows"

Date: 
Wed, 02/11/201612:00-13:30
Location: 
Danciger B building, Seminar room
Lecturer: Mr. Ehud Yarom
Affiliation: Racah Institute of Physics,
The Hebrew University of Jerusalem
Abstract:
Rotating turbulent flows are very common in
geophysical and astrophysical systems, but it is
still unclear which framework should be used
for their description. On the one hand, some
properties of rotating turbulence can be
described by 2D turbulence statistics. On the
other hand, the linearized equation of motion
for rotating systems supports 3D linear waves –
the Coriolis driven inertial waves. Adding
nonlinear interactions to these waves might
give a better, 3D, description of rotating
turbulence.
I’ll present experiments conducted in rotating
tank at moderate Reynolds and small Rossby
numbers. The results show both properties of
2D statistics and of 3D interacting waves. I’ll
begin by showing that the energy spectrum has
an inverse energy cascade quantitatively similar
to that of 2D turbulence. Next I’ll show that for
the same flow parameters, the 3D energy
spectrum is concentrated around the dispersion
relation of inertial waves. Finally I’ll use the
broadening of the dispersion relation to
measure the time scales of nonlinear wave
interactions, and find a relation between these
time scales to the flow parameters. I’ll argue
that there is a range of parameters in which the
system can be described as an ensemble of
interacting waves.