Alongshore velocities and turbulence in the swash and surf zone forced by oblique, monochromatic waves on smooth and rough impermeable beaches

IF 4.5 2区工程技术 Q1 ENGINEERING, CIVIL

Coastal Engineering Pub Date : 2025-06-20 DOI:10.1016/j.coastaleng.2025.104812

Alexandra E. Schueller , Thomas Pendergast , Kelsey Fall , Hyungyu Sung , Dawson Ethier , Ryan P. Mulligan , Jason Olsthoorn , Nimish Pujara , Jack A. Puleo

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引用次数: 0

Abstract

Wave breaking on beaches drives complex nearshore flow patterns and turbulence. A series of controlled laboratory experiments were conducted to better understand swash and surf zone hydrodynamics on smooth and rough planar impermeable beaches under obliquely incident waves. The experiments were performed in a 26.0 m long, 20.6 m wide, and 1.0 m deep wave basin using a fixed concrete beach with a 1:10 slope. The beach surface was roughened through sandblasting following smooth surface experiments to allow a direct comparison between smooth and rough bed conditions. Regular waves with heights of 0.10 m, 0.125 m, and 0.15 m and a period of 2.0 s were generated with the wave paddle positioned at angles of 0°, 10°, and 20° with respect to the beach. An array of sensors recorded high-frequency data on water surface elevations and velocities at multiple cross-shore positions. Differences in the cross-shore velocities were most evident near the breaker zone, with peak onshore velocities approaching 0.8 m/s. Bed roughness was found to delay wave breaking and modulate velocity profiles compared to smooth bed conditions. Alongshore velocities remained predominantly positive, indicating consistent wave-driven mean flow along the beach, generally increasing with wave paddle angle, and measurements over the smooth bed contained larger nearbed gradients and alongshore flows during flow reversal. Mean nearbed turbulent kinetic energy (k) in the surf zone was on the order of 10⁻³ m²/s². Roughness resulted in an increase of nearbed

k

of approximately 12 % at the sensor closest to wave breaking. Analysis of nearbed Reynolds stresses close to the wave breaking location showed roughly a factor of 2 increase for beach normal waves compared to obliquely incident waves. This may suggest influence of reflections off of the beach increased by the intermediate-to-steep slope in this study.

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在平滑和粗糙的不透水海滩上，斜的、单色的波浪迫使冲刷和冲浪区的沿岸速度和湍流

海滩上的波浪破碎驱动了复杂的近岸流动模式和湍流。为了更好地理解斜入射波作用下光滑和粗糙平面不透水海滩上的冲刷和冲浪带水动力，进行了一系列的室内对照实验。实验在26.0 m长，20.6 m宽，1.0 m深的波浪池中进行，采用固定的混凝土海滩，坡度为1:10。在光滑表面实验之后，通过喷砂对海滩表面进行粗糙处理，以便直接比较光滑和粗糙的床况。当桨叶与海滩的角度分别为0°、10°和20°时，产生高度为0.10 m、0.125 m和0.15 m的规则波，周期为2.0 s。一系列传感器记录了多个跨岸位置的水面高度和速度的高频数据。在破碎带附近，跨岸速度的差异最为明显，陆上速度峰值接近0.8 m/s。与光滑的床面条件相比，粗糙的床面可以延迟波的破碎和调制速度剖面。沿海岸流速主要为正，表明沿海滩的平均流量与波浪驱动的一致，通常随着波桨角的增加而增加，并且在平滑床上的测量结果包含更大的近床梯度和流动反转期间的沿海岸流量。冲浪区的平均近床湍流动能(k)约为10−3 m2/s2。在最接近破波的传感器处，粗糙度导致近床k增加约12%。对靠近破波位置的近床雷诺兹应力的分析表明，与斜入射波相比，海滩正常波大约增加了2倍。这可能表明，在本研究中，中陡坡增加了海滩反射的影响。

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来源期刊

Coastal Engineering 工程技术-工程：大洋

CiteScore

9.20

自引率

13.60%

发文量

审稿时长

3.5 months

期刊介绍： Coastal Engineering is an international medium for coastal engineers and scientists. Combining practical applications with modern technological and scientific approaches, such as mathematical and numerical modelling, laboratory and field observations and experiments, it publishes fundamental studies as well as case studies on the following aspects of coastal, harbour and offshore engineering: waves, currents and sediment transport; coastal, estuarine and offshore morphology; technical and functional design of coastal and harbour structures; morphological and environmental impact of coastal, harbour and offshore structures.