AN EXPERIMENTAL INVESTIGATION OF BREAKING WAVES PRODUCED BY A TOWED HYDROFOIL
AN EXPERIMENTAL INVESTIGATION OF BREAKING WAVES PRODUCED BY A TOWED HYDROFOIL
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DOI：
10.1098/rspa.1981.0127
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发表时间：
1981-01-01
期刊：
影响因子：
--
通讯作者：
DUNCAN, JH
中科院分区：
文献类型：
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作者：
DUNCAN, JH
本文介绍了恒定水深和恒速拖曳水下二维水翼所产生的破碎波的试验结果。波浪场由一个破碎器和一系列较低的、不破碎的波组成。破碎机在其前坡上有一小片湍急的水流，这一区域称为破碎区。测量了表面高度分布、波浪尾迹平均水平速度的垂直分布和尾迹的垂直厚度。结果支持这样的假设，即破碎区沿前坡施加的剪力等于其在该方向上的重量分量。这种作用力会产生一种湍流的、动量不足的尾迹，类似于无限流体中拖曳的二维物体的尾迹。尾迹的垂直厚度与破碎器后距离的平方根成正比。动量亏近似等于与破碎器具有相同相速度的Stokes波的最大动量通量。表面轮廓测量产生了几个结果：描述波浪的合适的自变量是它的速度和它的前表面的斜率。破碎波长与速度的关系遵循有限振幅斯托克斯波动方程。破碎区的幅度和垂直范围都与相速度的平方成正比，但它们不是波前面斜率的函数。破碎区的长度有一个小的振荡，其规则周期为4.4个周期，即相速度等于水翼速度的波的周期。振荡的幅度随着时间的推移而减小。这种振荡被认为是由于箔片从静止状态启动时产生的波分量所致。
This paper presents the results of experiments on breaking waves produced by towing a submerged, two-dimensional hydrofoil at constant depth and speed. The wave field consists of a breaker followed by a train of lower, non-breaking waves. The breaker has a small zone of turbulent water riding its forward slope; this zone is called the breaking region. Measurements were made of surface height profiles, the vertical distribution of mean horizontal velocity in the wake of the wave, and the vertical thickness of the wake. The results support the hypothesis that the breaking region imparts a shearing force along the forward slope equal to the component of its weight in that direction. The force produces a turbulent, momentum-deficient wake similar to the wake of a towed, two-dimensional body in an infinite fluid. The vertical thickness of the wake grows in proportion to the square root of distance behind the breaker. The momentum deficit is approximately equal to the maximum momentum flux of a Stokes wave with the same phase speed as the breaker. The surface profile measurements yield several results: the proper independent variables describing the wave are its speed and the slope of its forward face. The relation between breaking wavelength and speed follows the finite-amplitude Stokes wave equation. The amplitude and the vertical extent of the breaking region are both proportional to the phase speed squared; however, they are not functions of the slope of the forward face of the wave. The breaking region has a small oscillation in its length with a regular period of 4.4 the period of a wave with phase speed equal to the hydrofoil speed. The amplitude of the oscillation diminishes with time. It is believed that this oscillation is due to wave components produced when the foil is started from rest.