Low-dimensional modelling of dynamical systems applied to some dissipative fluid mechanics

Abstract

Consider briefly the equations of fluid dynamics — they describe the enormous wealth of detail in all the interacting physical elements of a fluid flow — whereas in applications we want to deal with a description of just that which is interesting. In a wide variety of situations, simple approximate models are needed to perform practical simulations and make forecasts. I overview the derivation, from a mathematical description of the detailed dynamics, to accurate and complete low-dimensional models of the interesting dynamics in a system. The development of centre manifold theory and associated techniques puts this modelling process on a firm basis. The geometric viewpoint of dynamical systems theory greatly enriches our approach.