Instability and Transition in Buoyancy-Induced Flows

Abstract

Publisher Summary This chapter focuses on instability and transition in buoyancy-induced flows. Density differences in fluids, interacting with the gravitational field, produce an immense diversity of buoyancy forces and flow configurations in environment, in enclosures, and in the processes of technology. The atmosphere engine is driven by differences in temperature, water content, and water vapor concentration and by radiation. Laminar flows become unstable, to ever-present disturbances, even at the small-size scales common in technological and in immediate environmental processes. The difference between the rates of laminar and turbulent transport is very large for most flow configurations. Therefore, the questions of how and when, or where a flow becomes turbulent have a direct effect on the accuracy and reliability of estimates of transport. This chapter discusses the initial instability characteristics of different types of buoyancy-driven flows, followed by the formulation of linear stability theory. New results are summarized as additions to knowledge in specific areas previously studied and as the results of new research directions. The chapter also sets forth the question of improving stability analysis, beyond the assumptions inherent in the boundary-layer and parallel-base-flow formulations.