Collaborative Research: The Physics of Thermal and Superfluid Turbulence

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This is a collaborative research project in the area of fluid turbulence. The participating institutions are the University of Oregon (UO) and the University of Maryland (UMD). The research involves three subprojects. First, at UO, controlled, laboratory investigations of turbulent convection are being performed, under conditions relevant to geophysics and astrophysics: Extremes of control parameters such as Rayleigh and Prandtl numbers are sought via a large convection cell, whose aspect ratio and surface roughness properties can be varied. Second, at UMD, advanced development of a cryogenic Particle Image Velocimetry (PIV) technique, usable in liquid helium, is being carried out. Third, homogeneous and isotropic turbulence is being studied at the highest Reynolds numbers in both classical (UMD) and super-fluids (UO, UMD), with dynamically similar apparatus allowing meaningful comparisons. The research program builds on apparatus and skills acquired under grant DMR95-29609. Both undergraduate and graduate students will participate in cutting edge interdisciplinary research. The training they receive will prepare them for careers in academe, government or industry. Fluid turbulence is ubiquitous in nature and engineering. It is a complex non-linear phenomenon that is a paradigm for problems with many degrees of freedom, from economics to fracture dynamics. Further progress, however, requires significant input from experiments that truly "push the envelope." Technology is being developed for this task in a collaboration between the University of Oregon and the University of Maryland. In particular, ultra-high levels of turbulent intensity are attained under controlled laboratory conditions using low temperature helium, which has the lowest viscosity of any known fluid. These experimental efforts are helping to catapult fluid turbulence from the status of "the last important unsolved problem in classical physics," with possible applications to many branches of science and numerous practical problems. A specific area that is addressed is turbulent thermal convection, which is a fundamental and important part of all atmospheric and oceanic circulations, the intense motions inside stars, and myriad engineering processes that involve heat transport. Both undergraduate and graduate students will participate in cutting edge interdisciplinary research. The training they receive will prepare them for careers in academe, government or industry.