Interacting Vortices, their Formation and Evolution

University Of Pittsburgh, Pittsburgh PA

Investigators

Abstract

Non-Technical: Vortices are ubiquitous in fluids and can form on scales as small as a fraction of a millimeter to as large as hundreds of kilometers. The formation of hurricanes is just one of the extreme examples of large- scale atmospheric phenomenon, which can have devastating consequences. This proposal is aimed at understanding fundamental physics that governs the formation, interaction, and evolution of vortices in a thin sheet of fluid that behave two dimensionally. It is believed that if fluid flow is predominantly two dimensional and turbulent, as in the atmosphere and in oceans, the flow can self organize into large, power structures. A mathematical theory, similar to thermodynamic theory of mixing of chemicals, has been formulated to explain this remarkable process. This proposal is an attempt to test such a theory using well-controlled laboratory experiments. A significant part of this research is to educate and train students, at different levels, who will be the new to science and engineering. The research project itself is very attractive to students because the physical phenomena are intriguing and visually pleasing. Technical: This proposal is aimed at understanding fundamental physics that governs the formation, interaction, and evolution of vortices in thin sheets of fluid that behave two dimensionally. This latter property prevents vortex stretching and is believed to be responsible for the formation of large-scale coherent structures with remarkable stability. Unlike vortices occurring in nature, laboratory vortices can be created in a controlled manner, allowing detailed studies to be carried out. It has been postulated that stability of these large-scale coherent structures results from the system being close to a unique state governed by the principle of maximum mixing entropy. This is an important hypothesis and our experiment is designed to test whether this entropy principle works for vortices as well as for an ordinary thermodynamic system. A significant part of this research is to educate and train students who will be new to science and engineering. The research project itself is very attractive to students of all age groups because the physical phenomena are intriguing but visually pleasing.