3D Lagrangian modelling of saltating particles diffusion in turbulent water flow
3D Lagrangian modelling of saltating particles diffusion in turbulent water flow
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DOI：
10.2478/s11600-012-0003-2
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发表时间：
2012-12-01
期刊：
影响因子：
2.3
通讯作者：
Rowinski, Pawel M.
中科院分区：
文献类型：
--
作者：
Bialik, Robert J.;Nikora, Vladimir I.;Rowinski, Pawel M.
提出了固体球形颗粒在明渠流床上跃移的 3D 拉格朗日模型，解释了湍流引起的机制，并将其用作该研究的关键工具。讨论了传统 2D 模型和提出的 3D 跳跃模型之间的差异，并强调了 3D 模型的优点。特别是，3D 模型包括允许生成 3D 流速场的特殊程序。该过程基于这样的假设：在距床层任何距离处，流向、垂直和横向速度分量的频谱都是已知的。 3D 模型用于识别和量化湍流对颗粒夹带和跃变的影响。粒子轨迹的分析侧重于其扩散性质，阐明：（i）粒子迁移率参数的影响； (ii) 河床地形的影响； (iii) 湍流的影响。具体而言，给出了描述上述对方差时间变化的影响的数值模拟结果。此外，还显示了偏度和峰度随时间的变化，这很可能反映了湍流对颗粒扩散的影响。对于每个所研究的流动条件，可以自信地识别出两种不同的扩散机制（局部和中间）。
A 3D Lagrangian model of the saltation of solid spherical particles on the bed of an open channel flow, accounting for turbulence-induced mechanisms, is proposed and employed as the key tool of the study. The differences between conventional 2D models and a proposed 3D saltation model are discussed and the advantages of the 3D model are highlighted. Particularly, the 3D model includes a special procedure allowing generation of 3D flow velocity fields. This procedure is based on the assumption that the spectra of streamwise, vertical and transverse velocity components are known at any distance from the bed. The 3D model was used to identify and quantify effects of turbulence on particle entrainment and saltation. The analysis of particle trajectories focused on their diffusive nature, clarifying: (i) the effect of particle mobility parameter; (ii) the effect of bed topography; and (iii) the effect of turbulence. Specifically, the results of numerical simulations describing the abovementioned effects on the change in time of the variance are presented. In addition, the change in time of the skewness and kurtosis, which are likely to reflect the turbulence influence on the spread of particles, are also shown. Two different diffusion regimes (local and intermediate) for each of the investigated flow conditions are confidently identified.