The volume represents a lifetime's work of the author, for many years the Stephen P Timoshenko Distinguished University Professor of Fluid Mechanics of the University of Michigan. The papers selected treat the dynamics of stratified or rotating fluids, internal or surface waves, hydrodynamic stability, jets and plumes, flow in porous media, and certain aspects of hydrodynamics in magnetic or electric fields. When the papers are viewed in perspective, heterogeneity, whether in density, entropy, circulation, viscosity, or in some quantity which can be called magnetic circulation, seems to be a recurring theme in the phenomena investigated. It provides a general framework through which the understanding of the various phenomena is facilitated by the satisfying similarity underlying their seeming diversity.Contents: Part A: Stratified Flows and Internal WavesPart B: Theory of Hydrodynamic StabilityPart C: Gravity WavesPart D: Jets, Plumes and DiffusionPart E: GeneralReadership: Engineers and physicists working on fluid mechanics, applied mathematicians and geophysical fluid dynamicists.Key Features:Addresses many fundamental and basic questions in the general domain of modeling physical knottingOffers distinct perspectives of the frontier areas where topology, computation, physics and the life science overlap