Stochastic Approach to Sediment Transport Process by Wave Superimposed on Current.

即使在边界几何形状不均匀、水流不稳定的情况下，非平衡输沙过程也可以用广义随机模型进行合理系统的描述，该模型由泥沙的取沙速率、步长、移动周期和移动速度组成。砂粒的拾取速率、步长、移动周期和移动速度可以根据砂粒的运动方程进行动态评估，并特别参考流动结构和边界形态的概率因素。针对不同边界条件下的不同类型的水流，给出了非平衡输沙规律的广义表达式和各自的沙运动特征。得到了下列条件的实用而简单的表达式。(1)在正弦变化的平面和床层结构上的稳定和不均匀流动；(2)三角形沙丘上的稳定和不均匀流；(3)以不同类型的流量线为特征的非定常流场；(4)伴随振荡流动的电流；(5)电流随波而动。对(1)~(4)两种情况进行了流场结构和层质输运过程的详细实验，收集了大量数据。所得的流场结构信息应用于上述砂土运动模型。所得结果与实验结果吻合较好。对于(5)的流型，根据收集到的其他研究人员的实验结果，对沙的运动特性进行了评价。理论公式与实验数据吻合较好。本文认为，广义随机输沙模型对空间非均匀非定常流动中非平衡河床运动是非常有效的。

Even if the boundary geometry is non-uniform and the flow is unsteady, non- equilibrium sediment transport processes are reasonably and systematically described by the generalized stochastic model , which are consisted of the pick-up rate, step length , moving period and moving speed of a sand particle. The pick-up rate, step length, moving period and moving speed of a sand particle can be dynamically evaluated in terms of the equation of motion of a sand particle with particular reference to the probabilistic factors of the flow structures and boundary configuration. The generalized expression for the non-equilibrium sediment transport law and the respective characteristics of sand movement are formulated for the various types of flows under the various boundary conditions.The useful and simple expressions for the below conditions have been obtained.(1) the steady and non-uniform flow over the sinusoidaly varying plane and bed configuration;(2) the steady and non-uniform flow over the triangular sand dunes;(3) the unsteady flow which are characterized the various types of discharge hydrograph;(4) the current accompanied with the oscillatory flow;(5) the current accompanied with the wave.The minute experiments for the cases of (1)-(4) were carried out concerning the flow structures and the bed load transport process, and a great deal of data were collected. The obtained informations for the flow structures are applied to the above-mentioned models for the sand movement. The obtained results show the good agreement with the experiments. For the type of flow of (5), the characteristics of sand movement are evaluated based on the collected experimental results by other researchers. The theoretical formulation agrees well with the experimental data.It is recognized that the generalized stochastic model for sediment transport process are very effective to the non-equilibrium bed load motion in the spatially non-uniform and unsteady flow.