Laboratory investigation of pressure gradients induced by plunging breakers
Laboratory investigation of pressure gradients induced by plunging breakers
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插入式断路器引起的压力梯度的实验室研究
DOI：
10.1016/j.coastaleng.2011.03.013
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发表时间：
2011
期刊：
影响因子：
--
通讯作者：
Rodolfo Silva
中科院分区：
文献类型：
--
作者：
A. Pedrozo‐Acuña;A. R. D. Alegría;A. Torres;E. Mendoza;Rodolfo Silva
这项研究提供了实验室观测的时空演变的压力场和梯度的俯冲波传播通过近岸地区。进行了实验，以获得浅水区、破碎区和冲浪区的压力-时间曲线和流体速度的详细测量。压力包络在所有测试中都显示出一致的形状，最小值出现在冲浪区，最大值出现在撞击点。特别是，研究了不同位置(浅水区、破碎区和冲浪区)不同位置的压力梯度的性质，揭示了冲击点的最大值。文中还研究了压力梯度与水平速度和局部加速度的关系。这项研究有助于阐明在最近的研究中发现的一个明显的矛盾，即关于冲浪和激流区域内局部加速度和压力梯度之间的关系。与以前的研究结果一致，浅化和破碎带的结果表明，局部流体加速可以用来解释压力梯度的贡献。相比之下，这一假设的正确性并不是在冲动区内建立的。在这一区域，确定了最小的压力梯度，并且几乎在整个摆动周期中，局部加速度为负(离岸)，这与以前的现场观测一致。因此，对于俯冲式断路器驱动的摆动，结果指向作用于局部加速度的平流项的重要性。此外，用有效的气泡图像测速(BIV)技术测量的速度场提供了对高掺气流动的定性描述，揭示了垂直速度的最大值与俯冲式破碎器撞击床层的波浪冲击有关。这些结果表明，需要对不同类型的波浪破碎下的压力梯度进行详细的表征。
This investigation presents laboratory observations on the spatio-temporal evolution of pressure fields and gradients induced by plunging waves propagating across the nearshore zone. Experiments were carried out to obtain detailed measurements of pressure time-curves and fluid velocities across the shoaling, breaking and swash zones. Pressure envelopes showed a consistent shape in all tests, with minimum values in the swash zone and maximum values at the impinge points. In particular, the nature of the pressure gradient at different locations (shoaling, breaking and swash zones) across the impermeable bed is investigated, revealing maximum values at the impact points. The relationship of the pressure gradient to horizontal velocity and local acceleration is also examined. This investigation enabled the elucidation of an apparent contradiction identified in recent works regarding the relationship between local acceleration and pressure gradient within the surf and swash zones. Consistent with findings of prior studies, results in the shoaling and breaking zone indicated that local fluid accelerations can be used to account for the contribution of pressure gradients. In contrast, the validity of this assumption is not established within the swash zone. In this region, minimum pressure gradients are identified and local acceleration is negative (offshore) for almost the whole swash cycle, consistent with previous field observations. Thus, for plunging breakers driven-swash, results point toward the significance of the advective terms acting against local acceleration. Furthermore, measurements of the velocity field by a validated Bubble Image Velocimetry (BIV) technique provide a qualitative description of the highly aerated flow, revealing that maximum values of vertical velocities are associated with the wave-impact from a plunging breaker impinging on the bed. These results indicate the need for a detailed characterisation of the pressure gradient under different types of wave breaking.
影响因子：
2.9
作者：
G. Masselink;P. Russell;C. Blenkinsopp;Ian L Turner
通讯作者：
G. Masselink;P. Russell;C. Blenkinsopp;Ian L Turner