波浪边界层在斜坡上的动力变化及其对泥沙输移的影响

Wave boundary layer plays an important role in the mechanism of coastal sediment transport and morphological evolution. Existing studies on wave boundary layer have been mainly focused on the cases above a horizontal seabed. Over a natural sloping seabed, however, the wave boundary layer processes show significant difference. This study is to investigate the dynamic response of wave boundary layer to a sloping seabed and its effects on sediment transport. Based on wave theory and mathematical methods, a new second-order governing equation of wave boundary layer will be derived, which considers bathymetry effects, wave transformation, wave asymmetry and the interaction between wave and wave-induced currents. A physical experiment will be conducted to measure wave characteristics, boundary layer flow and bottom shear stress under different wave and seabed conditions, including wave shoaling, breaking and different slope angles. The experimental data will be used to parameterize the spatial and temporal variations in wave boundary layer dynamics. On the basis of the above work, 2DV wave boundary layer model and sediment transport model will be developed. The model will be verified with the measured data and a series of numerical experiments will be carried out to reveal the dynamic response of wave boundary layer to a sloping seabed and its effects on sediment transport and morphology change. In particular, the distinct physical mechanisms and dominant forcings under various wave and seabed conditions will be clarified. This study can provide a better understanding of the mechanism of coastal morphological evolution under complex bathymetry and hydrodynamic conditions and a useful reference for the development, management and protection in coastal regions.

波浪边界层是海岸泥沙运动与地貌形态演变的重要动力机制。已有的基础研究大多基于平底地形，但与实际中斜坡海床上的动力过程还存在较大差异。本课题着眼于近底小尺度动力结构，研究波浪边界层在斜坡上的动力变化及其对泥沙输移的影响。应用波浪理论和数值分析方法，推求综合考虑地形变化、波浪变形、非对称波形和波浪－波生流相互作用的二阶波浪边界层控制方程式。通过物模试验获取不同工况下的波要素、边界层流速剖面和床面剪应力，总结波浪浅化和破碎条件下边界层动力结构的变化规律。建立全面反映斜坡地形影响的垂向二维波浪边界层传播变形数学模型和泥沙运动数学模型，在实验数据验证的基础上，探讨不同波浪传播形态下各物理过程的影响机制和主导动力因素，揭示波浪边界层在斜坡上的动力变化特性及其对泥沙输移和床面冲淤演变的影响。本课题研究有助于更深入了解复杂地形和水动力条件下的海岸泥沙运动和地形演变规律，为海岸开发、治理与防护提供科学依据。

波浪边界层是海岸泥沙运动与地貌形态演变的重要动力机制。已有的基础研究大多基于平底地形，但与实际中斜坡海床上的动力过程还存在较大差异。本项目研究着眼于近底小尺度动力结构，综合采用理论分析、物模试验和数值模拟等手段，推导了综合考虑地形变化、波浪变形、非对称波形和波浪-波生流相互作用的二阶波浪边界层控制方程式，开展了波浪在斜坡上传播变形条件下的边界层物理模型试验，建立了全面反映斜坡地形影响的波浪边界层传播变形与泥沙运动数学模型，阐明了波浪边界层在斜坡上的动力变化及其对泥沙输移的影响机理，为更深入了解复杂地形和水动力条件下的海岸泥沙运动和地形演变规律，以及岸滩保护、海工建筑物、人工养滩等实际海岸工程建设提供科学依据。通过项目组全体成员的共同努力，本项目研究达到了预期目标。发表论文8篇，其中SCI检索论文5篇、EI检索论文1篇。获2013年中国海洋工程科学技术奖二等奖，获美国土木工程师协会（ASCE）主办的水道港口与海岸海洋工程期刊《ASCE Journal of Waterways, Port, Coastal, and Ocean Engineering》2014年度最佳论文奖（Best Paper Award）。培养博士研究生2名、硕士研究生3名。项目负责人入选江苏省“333高层次人才培养工程”中青年科学技术带头人。