Turbulence on a Free Surface

这个研究项目涉及流体动力学。它是由材料研究部门的凝聚态物理项目和化学和运输系统部门的流体动力学和水力学项目共同资助的。它是对封闭流体自由表面上的湍流的研究。流体运动或湍流是通过观察在空气/水界面夹带的小颗粒的平面内、水平速度分量来检测的。一个大的激光照亮表面的粒子，这些粒子被一台快速摄像机跟踪。在表面上和表面以下，流体是不可压缩的；这意味着表面速度，相反，是可压缩的。因为能量和涡度可以与下面的流体自由交换，所以柯尔莫哥洛夫类型的维度参数是不可用的，所以必须求助于计算机模拟来模拟运动。一个有趣的现象是粒子倾向于聚集而不是分散。这些观测结果与实际问题有关，例如湍流海面上污染物的扩散和空气/水界面上生物有机体的生长速度。教育部分完全集中在本科生身上。实验技术是计算机密集型的，为物理专业学生、工程师和对模式识别问题感兴趣的人提供了一个很好的训练基地。该流体动力学湍流研究项目由材料研究部门的凝聚态物理项目和化学与运输系统部门的流体动力学和水力学项目共同资助。当物体在空气或海洋中快速移动时，总是会出现湍流。为了改善天气预报和更好地应对自然灾害和人为灾害，如风暴和污染泄漏，了解湍流的复杂现象是必要的。这里的重点是漂浮在湍流水体上的小颗粒的运动。这些“漂浮物”可以被认为是浮标、船只或漂浮污染物运动的替代品。海面上的湍流有一种不同寻常的效果，它会使漂浮物聚集在一起，而它们则分散在大海或空气中的其他地方。这项研究是首批在实验室控制条件下进行的研究之一。教育部分完全集中在本科生身上。这项研究利用尖端技术来跟踪粒子运动（高速摄像机和强大的新型固态激光器），为基础科学或工程专业的学生提供了一个很好的训练基地。

This research project deals with fluid dynamics. It is co-funded between the Condensed Matter Physics Program In the Division of Materials Research and the Fluid Dynamics and Hydraulics Program in the Division of Chemical and Transport Systems. It is a study of turbulence at the free surface of a closed body of fluid. The fluid motion or turbulence is detected by observing the in plane, horizontal velocity components of small particles entrained at the air/water interface. A large laser illuminates the surface particles, which are tracked with a fast camera. At points at and below the surface, the flow is incompressible; this implies that the surface velocity is, by contrast, compressible. Because energy and vorticity can be freely exchanged with the fluid below, Kolmogorov-type dimensional arguments are not available, so one must turn to computer simulations to model the motion. One phenomenon of interest is the tendency of particles to cluster rather than disperse. The observations are relevant to practical issues such as dispersal of pollutants at the surface of a turbulent sea and the growth rate of biological organisms at an air/water interface. The educational component is focused entirely on undergraduate students. The experimental techniques, which are computer intensive, provide an excellent training ground for physics majors, engineers, and those interested in pattern recognition issues. They will be prepared for a range of careers in academe, industry and governmentThis fluid dynamics turbulence research project is co-funded between the Condensed Matter Physics Program In the Division of Materials Research and the Fluid Dynamics and Hydraulics Program in the Division of Chemical and Transport Systems. Turbulence invariably appears when objects move rapidly through the air or the sea. An understanding of the complex phenomenon of turbulence is necessary in order to improve weather prediction and to better cope with natural and man-made disasters such as storms and pollution spills. The focus here is on the motion of small particles that float on a turbulent body of water. These 'floaters' may be thought of as a surrogate for the motion of buoys, ships, or floating pollutants. Turbulence at the surface has the unusual effect of causing the floaters to clump together, whereas they are dispersed elsewhere in the bulk sea or the air. This study is one of the first to be carried out under laboratory-controlled conditions. The educational component is focused entirely on undergraduate students. The research utilizes cutting-edge technology for tracking the particle motion (high-speed cameras and powerful new solid-state lasers) and provides an excellent training ground for students majoring in fundamental science or engineering.