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

在边界几何形状不均匀、水流不恒定的情况下，非平衡输沙过程可用广义随机模型来合理、系统地描述，该模型由泥沙颗粒的取沙率、步长、运动周期和运动速度组成。根据沙粒的运动方程，特别参考流动结构和边界形态的概率因子，可以动态地估计沙粒的拾取速度、步长、移动周期和移动速度。给出了不同边界条件下不同类型水流的非平衡输沙规律和各自的泥沙运动特征的一般表达式，得到了以下条件的实用而简单的表达式：(1)正弦变化的平面和床面上的恒定非均匀流，(2)三角形沙丘上的恒定非均匀流，(3)以各种类型的流量过程为特征的非恒定流，(4)伴随振荡流的水流，以及(3)以各种类型的流量为特征的非恒定流。(5)水流伴波。对(1)-(4)的水流结构和推移质输运过程进行了详细的试验，收集了大量的资料。将得到的水流结构信息应用于上述泥沙运动模型。计算结果与实验结果吻合较好。对于(5)型水流，根据其他研究人员收集的实验结果，对泥沙运动特性进行了评估。理论公式与试验结果吻合较好。研究表明，输沙过程的广义随机模型对空间非均匀非恒定流中的非平衡推移质运动是非常有效的。

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.