Japan STA Program: Turbulence Structure and Sediment- Transport Field near a Flow Obstruction at the Bed of a Hydraulically Rough Turbulent Boundary Layer

Schmeeckle 9803854该奖项支持马克·Schmeeckle博士在日本札幌的土木工程研究所(CERI)获得为期24个月的日本科学技术厅博士后奖学金。Schmeeckle博士将与CERI总干事Hitoshi Baba博士合作开展一项研究项目，题为“水力粗糙的湍流边界层底部的水流障碍物附近的湍流结构和泥沙传输场”。洪水期间对河流周围建筑物的泥沙冲刷是一个主要的工程问题。这样的冲刷可能导致结构损失或昂贵的维修费用。遗憾的是，冲刷的预报往往基于经验方法，缺乏物理上的了解，甚至比例尺模型也是困难的，因为几乎不可能同时准确地比例尺水流和泥沙场。以往基于物理的泥沙输运模型只考虑了简化湍流场中的平均水流条件，在复杂的水流条件下，如在河流建筑物周围，模型表现不佳。在这项研究中，一个新发展的模型，直接耦合瞬时近床速度和输沙场，将应用于圆柱形桥墩绕流的情况。为了实现这一目标，将收集码头周围近基床速度的高频测量数据。这些速度测量将被用来驱动泥沙输送模型，而泥沙输送又将被用来预测圆柱体周围冲刷剖面的演变。该项目的成功完成将使人们对河流建筑物周围的冲刷有一个物理上的了解。***

Schmeeckle 9803854 This award supports a 24 month Science and Technology Agency of Japan (STA) Postdoctoral Fellowship for Dr. Mark Schmeeckle at the Civil Engineering Research Institute (CERI) in Sapporo, Japan. Dr. Schmeeckle will work with Dr. Hitoshi Baba, General Director, CERI, on a research project entitled "Turbulence Structure and Sediment-transport Field Near a Flow Obstruction at the Bed of a Hydraulically Rough Turbulent Boundary Layer." The scour of sediment from around river structures during flood is a major engineering concern. Such scour can lead to the loss of the structure or expensive repairs. Unfortunately, the prediction of scour is often based on empirical methods with little physical understanding, and even scale models are difficult because it is nearly impossible to accurately scale both the flow and sediment transport fields simultaneously. Previous physically based sediment transport models only considered mean flow conditions in simplified turbulence fields and performed poorly in complex flow conditions such as around river structures. In this study a newly developed model, which directly couples the instantaneous near-bed velocity to the sediment transport field, will be applied to the case of flow around a cylindrical pier. To accomplish this goal, high-frequency measurements of near-bed velocities around the pier will be collected. These velocity measurements will then be used to drive the sediment transport model, and the sediment transport will in turn be used to predict the evolution of the scour profile around the cylinder. Successful completion of this project will result in a physically based understanding of scour around river structures. ***