PHYSICAL MATHEMATICS SEMINAR TOPIC: Borders of Disorder: in Turbulent Channel Flow SPEAKER: WILLEM V.R. MALKUS Department of Mathematics Massachusetts Institute of Technology ABSTRACT: A quantitative theory of the average features of turbulent flow in a channel is described without the introduction of empirical parameters. The critical elements herein include, first, from the Navier--Stokes equations, the determination of statistical stability conditions, which delimit the dissipation rate of the fluctuating fields, and second, a time--dependent stability study determining the properties turbulent boundary layer. The velocity fields satisfying these conditions, the averaged equations and the boundary conditions uniquely determine a mean velocity profile with a logarithmic layer, and the velocity defect observed in the interior of the flow, well within ten percent of the data. Computer confirmation of the several asymptotic estimates of the critical boundary eigenstructure can establish the limits of validity of the theory. DATE: TUESDAY, APRIL 23, 2002 TIME: 2:30 PM LOCATION: Building 2, Room 338 Refreshments will be served at 3:30 PM in Room 2-349 Massachusetts Institute of Technology Department of Mathematics Cambridge, MA 02139