A FINITE-DIMENSIONAL MECHANISM RESPONSIBLE FOR BURSTS IN FLUID MECHANICS

A simple finite-dimensional mechanism is described that appears to be responsible for the presence of bursts near onset of primary instability in a number of fluid systems. The manifestation of the mechanism differs dramatically from system to system, but the mechanism is common to all of them. The geometrical ideas behind the mechanism are discussed, and the results applied to three systems, (a) binary fluid convection, (b) natural doubly diffusive convection, and (c) Faraday oscillations in an almost circular container. Where possible the results are confronted with the results of direct numerical simulations in two or three dimensions.