Sheetflow simulator for numerical prediction of sediment transport rate

在片流状态下，短时间内输沙量大，因此片流输沙效应对预测海床剖面变化具有重要意义。由于存在高浓度沉淀物，大多数用于流量测量的传感器不能在片流条件下工作。此外，视频分析是研究片流输沙的有效工具，但需要耗费大量的时间。在本研究中，提出了两种发展沙片流分析的方法。一种是采用颗粒物质模型或DEN （distinct element method）对沙片流进行数值模拟；二是利用免费软件简化视频分析过程。除了这些方法外，还应研究自然海岸的一些重要因素作为泥沙输运过程的外部驱动力。因此，本研究的主要对象应为：(1)振荡水洞对沙片流的水力试验；(2)泥沙片流模拟数值移动床的研制；(3)自然海岸沉积物片流的外部驱动力（3- 1多向不规则波浪，3-2斜波上升，3-3波浪上升导致的渗流，3-4波浪传播导致的海床液化）。

In sheetflow regime, great amount of sediment is transported in short period of time, hence the effect of sheet flow sediment transport plays a significant role in the prediction of sea-bed profile change. Most of sensors for the flow measurement does not work in the sheetflow condition, due to the presence of a high concentration sediment. Furthermore, the video-film analysis, which is the effective tool to investigate the sheet flow sediment transport, requires the time-consuming processes.In this study, two approaches for the development of the analysis of sediment sheetflow are conducted. The one is the numerical modeling of the sediment sheet flow by the granular material model, or the DEN (distinct element method) ; the other is the simplified process of the video film analysis by the use of the free wares. In addition to these approaches, some significant factors in the natural coast should be investigated as the external driving forces of the sediment transport process. Hence the primal subjects of this study should be as follows : (l) the hydraulic experiment of sediment sheetflow by the oscillatory water tunnel ; (2) the development of numeral movable bed for the simulation of sediment sheetflow ; (3) the external driving forces of sediment sheetflow in a natural coast (3-l multi-directional irregular waves ; 3-2 obliquely wave run-up ; 3-3 seepage flow due to wave run-up ; and 3-4 liquefaction of sea bed due to propagating waves).