Elevation and velocity measurements of laboratory shoaling waves
Elevation and velocity measurements of laboratory shoaling waves
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实验室浅滩波的高程和速度测量
DOI：
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发表时间：
1981
期刊：
影响因子：
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通讯作者：
D. Inman
中科院分区：
文献类型：
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作者：
R. Flick;R. Guza;D. Inman
对单频实验室波的浅滩、破碎和孔洞区波高和轨道速度的测量表明，当能量通量守恒时，三阶Stokes理论可以预测乌塞尔数Ur = (H/ H)/(kh)2小于等于0(1)时波高变化和谐波增长。在Stokes区域的近处和断点之前，谐波幅值可以用余弦理论很好地描述。从理论上证明了波浪在斯托克斯区和余弦区之间存在一个平滑的过渡状态，波浪最终因暴跌而破裂。在接近破碎的波浪和钻孔中观测到的波浪剖面在垂直平面上的不对称是由于波列浅滩时谐波相对于主波的相位变化缓慢。相比之下，在斯托克斯和余弦波理论中，只有水平面上的不对称是可能的，因为这些经典解不允许谐波之间的相对相移。用热膜风速计进行的速度测量表明，破碎波作用下底部的“无组织”波动约为波诱导的“有组织”流的均方根幅值的一半。破浪和钻孔作用下的水面高程与底部速度的相关性表明，湍流对下沉波下的无组织流动的贡献大于溢出波下的无组织流动。
Measurements of wave elevation and orbital velocity in the shoaling, breaking, and bore regime of single-frequency laboratory waves show that third-order Stokes theory, when energy flux is conserved, predicts the wave height change and harmonic growth in the regime where the Ursell number Ur = (H/ h)/(kh)2 is 0(1) or less. Shoreward of the Stokes region and up to the breakpoint, harmonic amplitudes are well described by the cnoidal theory. It is shown theoretically that a smooth transition regime exists between Stokes and cnoidal regions for waves which eventually break by plunging. The wave profile asymmetry about the vertical plane observed in near-breaking waves and bores is due to slow changes of phase of the harmonics relative to the primary wave as the wave train shoals. By contrast, only asymmetry about the horizontal plane is possible in the Stokes and cnoidal wave theories, since these classical solutions allow no relative phase shifts between harmonics. Velocity measurements made with hot-film anemometers show that ‘unorganized’ fluctuations at the bottom under breaking waves are of the order of half the rms amplitude of the wave-induced ‘organized’ flow. The correlation between surface elevation and bottom velocity under breakers and bores suggests that turbulence contributes more strongly to the unorganized flow at the bottom under plunging than under spilling waves.