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

即使在非均匀边界和非恒定水流条件下，非平衡输沙过程也可以用广义随机模型进行合理而系统的描述，该模型由沙粒的挟沙率、步长、运动周期和运动速度组成。根据沙粒运动方程，并结合水流结构和边界形态的概率因素，可以动态地计算沙粒的拾取率、步长、运动周期和运动速度。本文导出了各种边界条件下各种水流的非平衡输沙规律的一般表达式和各自的泥沙运动特性，并得到了下列条件下实用而简便的表达式。(1)本文对三角形沙丘上的非恒定流、非均匀流、非恒定流、振荡流、非恒定流和振荡流的特征进行了研究。（5）波浪伴流，对（1）-（4）两种情况下的水流结构和推移质输移过程进行了详细的试验研究，收集了大量的试验资料。所获得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）的流动类型，基于其他研究人员收集的实验结果来评估沙运动的特性。理论计算结果与试验结果吻合较好，认为泥沙运动的广义随机模型对空间非均匀非恒定流中的推移质不平衡运动是非常有效的。

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.