【摘要】 涌潮是一种对涉水建筑物冲击巨大的非线性强间断流,实现涌潮的小尺度精细模拟是分析涉水建筑物在涌潮作用下结构稳定性的前提。采用大涡模拟(LES)技术求解N-S方程,利用流体体积法(VOF)实现对自由水面的追踪,边界上给定基于涌潮理论公式推导出的涨潮流速与水深条件,进行了涌潮的小尺度精细模拟。结果表明,数值模拟得到的涌潮传播速度与理论值比较接近,Fr<1.3时为波状涌潮,Fr>1.5时为旋滚涌潮,涌潮形态分区与前人的试验成果吻合。在涌潮传播过程中,潮头处流速最大,且表层流速波动幅度始终大于中低层流速波动幅度,旋滚涌潮潮头水体紊动比波状涌潮强烈。模拟结果同时表明涌潮潮前水深与涌潮高度是影响潮头流速波动和形态的主要因素。上述涌潮模拟方法可为涌潮河段涉水建筑物的结构设计及安全评估提供参考。更多还原

【Abstract】 The tidal bore is a kind of nonlinear strong discontinuous flow that has great impact on wading structures. The small-scale fine simulation of the tidal bore is the premise for analyzing the structural stability of the wading structures under tidal action. The large eddy simulation technique(LES) is used to solve Navier-Stokes(N-S) equations, and the volume of fluid(VOF) is selected to track the free water surface, and the boundary condition is determined by the tidal theory based on the tidal velocity and water depth conditions. The research results show that the tidal bore propagation velocity obtained by numerical simulation is close to the theoretical values. When Fr<1.3, the tidal bore is undular and is characterized by a marked roller when Fr>1.5. The zoning of tidal bore morphology is consistent with the previous experimental results. During the tidal bore propagation process, the flow velocity at the tidal head is the largest, and the fluctuation of the surface velocities is always greater than the fluctuation of the velocity in the middle and lower layers. The lateral motion of the breaking bore head is stronger than the undular tidal bore. The simulation results also indicate that the water depth before the tidal bore and the height of the tidal bore are the main factors affecting the fluctuation and shape of the tidal head velocity. The simulation method of the tidal bore provides technical support for structural design and safety assessment of the wading structures in the tidal bore reach.更多还原