Sheetflow simulator for numerical prediction of sediment transport rate

在片状水流条件下，短时间内输沙量大，因此片状水流输沙量的大小对预测海床剖面变化具有重要意义。由于高浓度泥沙的存在，大多数流量传感器不能在片流条件下工作。此外，作为研究片状水流泥沙运动的有效工具，影视分析需要耗时较长的过程。一种是用颗粒材料模型或DEN(离散单元法)对泥沙席流进行数值模拟；另一种是用自由软件简化了录像片的分析过程。除了这些方法外，自然海岸中的一些重要因素也应该作为泥沙输送过程的外部驱动力进行调查。因此，本研究的主要内容应包括：(L)摆动水洞泥沙席流水力试验；(2)泥沙席流数值模拟动床的研制；(3)天然海岸泥沙席流的外部驱动力(3-L多向不规则波；3-2斜浪抬高；3-3波浪抬高渗流；3-4波浪传播引起的海床液化)。

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).