Vortices, complex flows and inertial particles
Vortices, complex flows and inertial particles
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DOI：
10.1007/s10494-007-9096-0
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发表时间：
2007-10-01
影响因子：
2.4
通讯作者：
Perkins, R. J.
中科院分区：
文献类型：
--
作者：
Hunt, J. C. R.;Delfos, R.;Perkins, R. J.
本文综述了高雷诺数下均匀流动和刚性边界附近涡结构的特性。通过分析主流特征和相关积分约束的动力学，推导出新的性质，包括平均涡流和体积速度之间的关系，内部波动的相对水平，以散装性能，和结构的稳定性和拓扑结构之间的连接。决定能量耗散和惯性粒子（具有有限下降速度）的运输的关键性质是平均应变率（Sigma）与平均涡度（Omega）的比率在结构上的变化。它示出了如何，一旦这样的颗粒被夹带到一个连贯的结构的旋涡区域，它们可以被运输在显着的距离，即使作为旋涡的增长和它们的内部结构是扭曲的内部湍流，旋转运动和刚性边界的存在。然而，如果涡流被应变运动强烈地扭曲，使得Sigma大于Omega，则夹带的颗粒被相当迅速地喷射。这些机制与以前的研究相一致的夹带和沉积颗粒在分散的两相流在平坦的表面上，并在海崖障碍物和沙丘。它们也在这里通过实验室观察和测量的50-200 μ m的颗粒夹带到圆形和非圆形的旋涡首先进入静止的空气，然后到刚性表面上放置平行和垂直于运动的方向的旋涡进行了更详细的测试。
The properties of vortical structures at high Reynolds number in uniform flows and near rigid boundaries are reviewed. New properties are derived by analysing the dynamics of the main flow features and the related integral constraints, including the relations between mean swirl and bulk speed, the relative level of internal fluctuations to bulk properties, and connections between the steadiness and topology of the structures. A crucial property that determines energy dissipation and the transport of inertial particles (with finite fall speed) is the variation across the structure of the ratio of the mean strain rate (Sigma) to the mean vorticity (Omega). It is shown how, once such particles are entrained into the vortical regions of a coherent structure, they can be transported over significant distances even as the vortices grow and their internal structure is distorted by internal turbulence, swirling motions and the presence of rigid boundaries. However if the vortex is strongly distorted by a straining motion so that Sigma is greater than Omega, the entrained particles are ejected quite rapidly. These mechanisms are consistent with previous studies of entrained and sedimenting particles in disperse two phase flows over flat surfaces, and over bluff obstacles and dunes. They are also tested in more detail here through laboratory observations and measurements of 50-200-mu m particles entrained into circular and non-circular vortices moving first into still air and then onto rigid surfaces placed parallel and perpendicular to the direction of motion of the vortices.