Collaborative Research: The Physics of Thermal and Superfluid Turbulence

这是一个流体湍流领域的合作研究项目。 参与机构是俄勒冈州大学（UO）和马里兰州大学（UMD）。 该研究涉及三个子项目。 首先，在UO，受控的，湍流对流的实验室调查正在进行，在相关的天体物理学和天体物理学的条件下：极端的控制参数，如瑞利和普朗特数是通过一个大的对流细胞，其纵横比和表面粗糙度属性可以改变。 第二，在UMD，正在进行可用于液氦的低温粒子图像速度测量（PIV）技术的高级开发。 第三，均匀和各向同性湍流正在研究在最高雷诺数的经典（UMD）和超流体（UO，UMD），与动态类似的设备允许有意义的比较。 该研究计划建立在授予DMR 95 -29609下获得的设备和技能的基础上。 本科生和研究生都将参与前沿的跨学科研究。 他们接受的培训将为他们在企业，政府或工业中的职业生涯做好准备。 流体湍流在自然界和工程中普遍存在。 它是一种复杂的非线性现象，是从经济学到断裂动力学的许多自由度问题的范例。 然而，进一步的进展需要来自真正“突破极限”的实验的重要投入。“俄勒冈州大学和马里兰州大学正在合作开发这项任务的技术。 特别是，在受控的实验室条件下，使用低温氦气获得超高水平的湍流强度，其具有任何已知流体的最低粘度。 这些实验努力有助于将流体湍流从“经典物理学中最后一个未解决的重要问题”的地位弹射出来，并可能应用于许多科学分支和许多实际问题。 一个具体的领域是湍流热对流，这是所有大气和海洋环流的基本和重要组成部分，恒星内部的激烈运动，以及涉及热传输的无数工程过程。 本科生和研究生都将参与前沿的跨学科研究。 他们接受的培训将为他们在企业，政府或工业中的职业生涯做好准备。

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.