Campuses:

Is turbulence stable?

Friday, April 16, 2010 - 11:00am - 11:45am
EE/CS 3-180
William Young (Scripps Research Institute)
Keywords: Jet, layer, potential vorticity, beta-plane,
stratified turbulence, Cahn-Hilliard equation, negative viscosity

Abstract: I'll discuss two examples of uniformly forced turbulent flows in
which quasi-steady structures spontaneously form. This results in the
intensity of turbulence becoming spatially inhomogeneous on length scales
larger than those of the eddies i.e., as argued by Owen Phillips in 1972, a
spatially homogeneous turbulent flow may be subject to a large-scale
instability.

The first example is stirring a fluid with strong gravitational stability
due to, for example, dissolved salt. The resulting stratified turbulence
produces well-mixed layers with uniform density, separated by strongly
stable steps in density. The second example is the formation of zonal jets
in forced-dissipative beta-plane turbulence.

I'll discuss the prospects of understanding these systems using models
related to the Cahn-Hilliard equation.





MSC Code: 
76Fxx
Keywords: