Eulerian and Lagrangian studies in surface flow turbulence
Eulerian and Lagrangian studies in surface flow turbulence
复制标题
表面流湍流的欧拉和拉格朗日研究
DOI：
--
复制
发表时间：
2004
期刊：
影响因子：
--
通讯作者：
J. Schumacher
中科院分区：
文献类型：
--
作者：
J. R. Cressman;J. Davoudi;W. Goldburg;J. Schumacher
本文介绍了自由表面湍流运动的实验和数值研究。流动实验上实现了一个充满水的表面搅拌以及低于表面的坦克的表面上。在数值上，它是由自由滑动边界条件建模。表面流是非常规的：它不是不可压缩的，在流体粘度为零的极限和没有外部驱动的情况下，动能和涡度拟能都不守恒，就像不可压缩的二维湍流一样。动态的被动拉格朗日示踪剂，平流在这样的流量占主导地位的快速变化的补丁的表面流发散。由于可压缩性，颗粒在多重分形质量分布中形成簇。还研究了粒子对和三重态的运动。的均方分离示出了一个扩展的范围与减少的标度指数相比，经典的理查森值。集群也表现在强烈变形的三角形内的三胞胎示踪剂。
Experimental and numerical studies of turbulent fluid motion in a free surface are presented. The flow is realized experimentally on the surface of a tank filled with water stirred well below the surface. Numerically, it is modelled by free-slip boundary conditions. The surface flow is unconventional: it is not incompressible and neither kinetic energy nor enstrophy is conserved in the limit of zero fluid viscosity and in the absence of external driving as is the case for incompressible two-dimensional turbulent flows. The dynamics of passive Lagrangian tracers that are advected in such flows are dominated by rapidly changing patches of the surface flow divergence. Owing to compressibility, particles form clusters within multifractal mass distributions. Also studied is the motion of pairs and triplets of particles. The mean square separation shows an extended range with a reduced scaling exponent in comparison with the classical Richardson value. Clustering is also manifest in strongly deformed triangles spanned within triplets of tracers.