River Plume Dynamics in Estuary

河流羽流、热羽流等死水的表面浮力排放主要表现为流场和密度场的三维结构，这在很大程度上受控于水平压力梯度和由排受水密度差和动量通量引起的层结。此外，它们的行为可能会根据周围沿海海域的流场和密度场以及河口附近的地理特征而发生变化。建立了一个具有自由水面的三维原始数值模型，用于研究河流羽流的扩散。湍流剪切力和湍流浮力通量用涡动粘性系数和扩散系数表示，通过与已有实验数据的比较，用经验公式考虑了层化效应，并将模型预测结果与…河的实验结果进行了比较更多的羽流和较小的密度弗劳德数，在赤石河进行的野外观测结果，以及洪水中的尤多河的红外图像。从而阐明了河流羽流在河口附近扩散的特有机制，即水流加速、河水发散和扬起现象。该数值模型已应用于入横流和复杂地理特征的河流羽流。特别是用k-epsilon湍流模型从科学的角度评价了河口地形展开角对河流羽流三维结构的影响。在更大的尺度上，Rossby变形半径、地球自转和浮力是引起沿岸强地转流的主要力量。因此，Yodo River的羽流沿着神户和Awaji岛的海岸线向右流动，在洪水情况下形成了一股狭窄的海岸急流。计算得到的密度场与NOAA卫星在8210号台风洪水过程中拍摄的红外图像有很好的一致性。然而，如果有潮汐流动，其产生的水流就会超过密度驱动的水流，从而增加河流羽流的潮汐漂移，除非海岸急流的传播速度太快。相反，密度效应有助于潮汐余流系统的形成。较少

Buoyant surface discharges into stagnant waters such as river plume and thermal plume are characterized by the three-dimensional structure of flow and density fields, which is for the most part controlled by horizontal pressure gradients and the stratification resulting from the density difference between discharged and receiving waters as well as momentum fluxes. Furthermore, their behaviors may change depending on the flow and density fields of ambient coastal seas and the geographical features near the river mouth. A three-dimensional, primitive numerical model with a free water surface is developed for examining the river plume spreading. Turbulent shear stresses and turbulent buoyant fluxes are expressed in terms of the eddy viscosities and diffusivities, in which the stratification effects are taken into account with empirical formulae through the comparison of numerical results with published experimental data.The model predictions are compared with experimental results of river … More plumes with small densimetric Froude numbers, field observation results performed in the Akashi River, and the infrared image of the YodoRiver in flood. As a result, the mechanism peculiar to river plume spreading near the river mouth is clarified; that is, the flow acceleration, the divergence of river water and the lift off phenomena. The numerical model has been applied to river plumes discharged into cross flows and into complicated geographical features. In particular, the effects of spreading angle of river mouth topology on the three-dimensional structure of river plumes are evaluated by using a k-epsilon turbulence model from the scientific point of view.On a larger scale, the Rossby deformation radius, the earth's rotation in addition to the buoyancy are the major forces that cause a strong geostrophic along-shore current. Consequently, the Yodo River plume flows to the right along the coastal line of Kobe and Awaji Island while forming a narrow coastal jet in the case of flood. The computed density field shows good agreement with the infrared image taken by the NOAA satellite during the flood flow of typhoon 8210. If there is a tidal flows, however, its producing current exceeds the density-driven current, enhancing the tidal excursion of the river plume unless the propagation speed of the coastal jet is too high. Instead, the density effect assists in the formation of the tidal residual current system. Less