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徐海珏, 吴金森, 白玉川. 波浪扰动下河口幂律异重流的动力场分布特性[J]. 力学学报, 2019, 51(6): 1699-1711. DOI: 10.6052/0459-1879-19-073
引用本文: 徐海珏, 吴金森, 白玉川. 波浪扰动下河口幂律异重流的动力场分布特性[J]. 力学学报, 2019, 51(6): 1699-1711. DOI: 10.6052/0459-1879-19-073
Xu Haijue, Wu Jinsen, Bai Yuchuan. DYNAMIC DISTRIBUTION OF POWER-LAW DENSITY CURRENT IN ESTUARY UNDER WAVE[J]. Chinese Journal of Theoretical and Applied Mechanics, 2019, 51(6): 1699-1711. DOI: 10.6052/0459-1879-19-073
Citation: Xu Haijue, Wu Jinsen, Bai Yuchuan. DYNAMIC DISTRIBUTION OF POWER-LAW DENSITY CURRENT IN ESTUARY UNDER WAVE[J]. Chinese Journal of Theoretical and Applied Mechanics, 2019, 51(6): 1699-1711. DOI: 10.6052/0459-1879-19-073

波浪扰动下河口幂律异重流的动力场分布特性

DYNAMIC DISTRIBUTION OF POWER-LAW DENSITY CURRENT IN ESTUARY UNDER WAVE

  • 摘要: 河口底层浮泥异重流的运动特性对于河口维持以及港口航道泥沙淤积过程具有重要的作用, 是海岸学科研究的关键内容, 也是热点内容之一. 本文首先综述了河口泥沙异重流研究的重要意义, 分析并总结了各家异重流理论模型的不同点和适应条件; 其次, 根据本文研究问题的实际需要, 构建了波浪与底泥相互作用的双层流体理论分析模式, 将上层流体简化为常见的牛顿体, 而将下层流体的流变关系设置为幂律函数, 研究了波浪作用下河口底部幂律异重流的流场特性. 这些特性包括:波浪速度场、底泥运动的流速场、不同密度影响下的压力场以及异重流泥面波与表面 波的波幅比等, 分析了泥层密度、波动圆频率以及底泥幂律指数对流场及界面波的影响. 研究发现, 在波浪扰动下, 两层流体交界处速度分量连续, 压强出现突变. 在下部泥层中, 水平速度幅值曲线存在极大值. 随着波动圆频率增加以及泥层密度与流动指数的减小, 界面处上下压强差值呈现增大的趋势. 本模型与实测波幅比的数据进行对比结果证实了模型的合理性.

     

    Abstract: The kinetic characteristics of floating mud in the estuarine bottom play an important role on the deposition process in harbors or channels and the maintenance of estuaries. And the study on them has become one of the focuses of coastal researchers. In this paper, the significance of the study on sediment density flow in estuaries is summarized firstly, the differences and the conditions of the functions applied in the rheological relation of the mud by many investigators are analyzed. Then, according to the actual needs of the research problem in this paper, a two-layer fluid model with the upper-layer fluid setting as a Newtonian one and the lower-layer fluid being simplified as Non-Newtonian, was established under the wave motion. Additionally, as one of the important functions, the power law is adopted as the constitutive relation of the fluid. The flow field of the density current is then studied, including the velocities, pressures of the two layers fluids, the wave amplitude ratio of the interface to the free surface and so on. Additionally, the influences of the mud density, the circular frequency and the power-law exponent on the flow field are discussed in details. It is found that the velocities of the both layers are consistent with each other at the interface, while the pressure has a sudden change due to the existence of the velocity gradient along z-axis. In the lower layer, there is an extreme point in the curve of horizontal velocity amplitude. The differences of the pressures between the two layers become greater, with the increase of the circular frequency or the decrease of the mud density as well as the power-law exponent. Finally, the comparisons between the calculated results and the experimental data prove the validity of the model.

     

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