CPM Seminar

Patterns in Turbulence

Laurette Tuckerman

Laboratoire de Physique et Mécanique des Milieux Hétérogènes
ESPCI Paris

Plane Couette flow near transition displays steady periodic oblique bands of alternating turbulent and laminar flow. Numerical simulations of the Navier-Stokes equations in a tilted domain show a rich variety of such patterns, including spatio-temporal intermittency, branching and travelling states, and localized states analogous to spots. Quantitative analysis of the Reynolds-averaged equations reveals that both the mean flow and the turbulent force are centrosymmetric and can be described by only three trigonometric functions, leading to a model of 6 ODEs. The transition is best described as a bifurcation in the probability distribution function of the first Fourier component.