Concepts and Examples of Rotating Fluids

Abstract

Planets and stars are rotating objects and large scale fluid motions relative to the planets solid body rotation are constrained by rotation. Theoretical treatment of these fluid motions must, therefore, include rotation effects and it is for this reason that most of the advances in the understanding of rotating fluids have been made in the context of Geophysical Fluid Dynamics (GFD) and Astrophysical Fluid Dynamics (AFD). GFD can be considered a special case of AFD and many approximations made in GFD (see for instance Pedlosky [1]) are not valid in AFD [2]. For example, in GFD horizontal scales of motion L are much less than the radius of the planet, allowing the use of a constant or linearly varying Coriolis frequency f=2Q. The fluid layer depth H is much less than L so that only the component of Q perpendicular to the planets surface needs to be considered. The Boussinesq approximation has also only limited validity in AFD. All the lectures in this course use approximations current in GFD when problems of geophysical interest are considered.