Coastal Engineering最新文献_第2页

Study on whitecapping dissipation process for wave modelling during tropical cyclones 用于热带气旋期间波浪建模的白浪消散过程研究

IF 4.2 2区工程技术 Q1 ENGINEERING, CIVIL

Coastal Engineering

Pub Date : 2024-10-28 DOI: 10.1016/j.coastaleng.2024.104650

Wenxuan Sun , Zhuxiao Shao , Bingchen Liang , Huijun Gao

The atmosphere-wave interaction is an important physical process during tropical cyclones. Understanding and modelling of this process are of great significance for the technical and functional design of coastal and harbor structures. At the high wind velocities of tropical cyclones, foams and sprays that are blown away from the sea form a slip layer between the atmosphere and the sea surface. This slip layer makes the atmosphere-wave interaction exhibit different characteristics compared with that at low wind velocities. The significant effect of this layer on the atmosphere is the reduction of aero-dynamical surface roughness, which has been used to improve the expression of the drag coefficient. On this basis, the effect of the slip layer on the sea surface is further explored in this study. The whitecap coverage may reach a low limit at high wind velocities, and a modified numerical method of whitcapping dissipation for the wave spectrum model is proposed based on the classic field observations of whitecaps. According to these observations, when developing waves appear, the variation characteristics of whitecap coverage are different from those of developed waves with low wind velocities. Thus, the critical friction velocity of wave states should be defined, which can be expressed by the threshold steepness of developed waves due to the negative correlation between wave age and wave steepness. The dissipation mode is then modified to gradually reach the limit with the increase of friction velocities, which is validated during 24 tropical cyclones measured with 26 buoys. The negative Bias of the default mode generally decreases with the increase of friction velocity, even reaching −0.8 m, while the Bias of the modified mode is mostly maintained between 0.2 m and −0.2 m.

大气-波浪相互作用是热带气旋期间的一个重要物理过程。对这一过程的了解和模拟对海岸和港口结构的技术和功能设计具有重要意义。在热带气旋的高风速下，被吹离海面的泡沫和喷雾在大气和海面之间形成滑动层。与低风速时相比，该滑动层使大气与波的相互作用表现出不同的特征。该滑动层对大气的重要影响是降低了空气动力表面粗糙度，从而改善了阻力系数的表达。在此基础上，本研究进一步探讨了滑动层对海面的影响。在高风速下，白帽覆盖率可能会达到一个较低的极限，根据白帽的经典现场观测结果，提出了一种改进的波谱模型白帽耗散数值方法。根据这些观测结果，当出现发展波时，白帽覆盖率的变化特征不同于低风速下的发展波。因此，应定义波浪状态的临界摩擦速度，由于波龄和波陡之间的负相关关系，该临界摩擦速度可以用发育波的阈值陡度来表示。然后修改消散模式，使其随着摩擦速度的增加逐渐达到临界值，这在用 26 个浮标测量的 24 个热带气旋中得到了验证。默认模式的负偏差一般随着摩擦速度的增加而减小，甚至达到-0.8 米，而修正模式的偏差大多维持在 0.2 米至-0.2 米之间。

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引用次数: 0

Wave attenuation by cultivated seaweeds: A linearized analytical model 栽培海藻的波浪衰减：线性化分析模型

IF 4.2 2区工程技术 Q1 ENGINEERING, CIVIL

Coastal Engineering

Pub Date : 2024-10-28 DOI: 10.1016/j.coastaleng.2024.104642

Zhilong Wei , Morgane Weiss , Trygve Kristiansen , David Kristiansen , Yanlin Shao

An analytical framework is presented to describe the attenuation of regular and irregular waves propagating over floating seaweed farms. Kelp blades suspended on longlines are modelled, as a first approximation, as rigid bars rotating around their upper ends. Assuming small-amplitude blade motions under low to moderate sea conditions, the frequency-dependent transfer function of the rotations can be obtained, with quadratic drag loads linearized. Subsequently, the hydrodynamic problem with regular waves propagating over suspended seaweed canopies is formulated using the continuity equation and linearized momentum equations with additional source terms in the vegetation region. Analytical solutions are obtained for attenuated regular waves with their heights decaying exponentially as they propagate over the canopy. These solutions are utilized as the basis for predicting wave attenuation of irregular waves while stochastic linearization of the quadratic drag loads is employed. In contrast to energy-conservation-based models, which assume the velocity profile follows linear wave theory, the present solution can predict the reduced velocity inside the canopy. The analytical solutions are validated against experimental data and verified against a numerical flow solver. The model is capable of resolving the wave attenuation, along with velocity profiles and phase lag. Drag and inertial force exhibit cancellation effects on wave decay and both affect phase lag.

本文提出了一个分析框架，用于描述在漂浮海藻养殖场上空传播的规则波和不规则波的衰减。悬挂在延绳上的海藻叶片被模拟为围绕其上端旋转的刚性条，这是第一种近似方法。假定叶片在中低海况下做小振幅运动，则可获得旋转的频率传递函数，并将二次阻力载荷线性化。随后，利用连续性方程和线性化动量方程以及植被区域的附加源项，提出了规则波在悬浮海藻冠上传播的流体力学问题。得到了衰减的规则波的解析解，这些波在冠层上传播时高度呈指数衰减。这些解法被用作预测不规则波浪衰减的基础，同时对二次阻力载荷进行随机线性化。与假定速度曲线遵循线性波理论的基于能量守恒的模型相比，本解决方案可以预测冠层内的减弱速度。分析解决方案与实验数据进行了验证，并与数值流求解器进行了验证。该模型能够解决波衰减、速度剖面和相位滞后问题。阻力和惯性力对波浪衰减有抵消作用，并且都会影响相位滞后。

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引用次数: 0

Exploring wind flow dynamics in foredune notches using Computational Fluid Dynamics (CFD) 利用计算流体动力学（CFD）探索前沙丘缺口处的风流动力学

IF 4.2 2区工程技术 Q1 ENGINEERING, CIVIL

Coastal Engineering

Pub Date : 2024-10-26 DOI: 10.1016/j.coastaleng.2024.104646

Thomas A.G. Smyth , Thomas Pagon , Ian J. Walker

Coastal dunes offer a wide range of valuable ecosystem services such as protection from erosion, flooding, sea-level rise, and provision of specialised habitat for endangered, endemic, or migratory species. Foredune blowouts and landward migrating parabolic dunes play an important role in many coastal dune settings creating ecological heterogeneity associated with inland sand transport, nutrient supply, and geomorphic disturbance processes. However, as coastal dunes globally are being increasingly stabilised by vegetation and declining in their ecological resilience and functionality, anthropogenic interventions, such as the removal of invasive species and excavation of foredune notches, have emerged to simulate and restore critical aeolian processes required to maintain dune morphodynamics and onshore sediment transport between the beach and inland dunes. This study employed computational fluid dynamics (CFD) modelling to investigate key controls on the wind flow dynamics and sand transport potential within idealised foredune notches of varying widths, slopes, and planform shape (rectangular vs. trapezoidal) for perpendicular and oblique incident wind directions. Compared with empirical findings from similarly engineered notches, our results show that notch width significantly influences shear velocity in the excavated notch ‘slot’, with narrower notches (25 m wide) enhancing wind flow acceleration and inland sediment transport potential. Spatial patterns of shear velocity throughout notches were also sensitive to incident wind direction, with maximum shear velocities, and consequent inland sand transport potential, occurring when winds were parallel to the orientation of the notch. On the lobes of the notches, shear velocity and sand transport potential were greatest during oblique winds. Our results suggest that a relatively narrow notch (e.g. 25 m as opposed to 50 m or 100 m), aligned with the prevailing wind direction, creates the most favourable conditions for transporting sediment from the beach to the dune behind. These findings underscore the importance of notch design in coastal dune restoration, offering critical insights for optimising interventions aimed at sustaining aeolian sediment transport from the beach to the hinterdune.

沿海沙丘提供了多种宝贵的生态系统服务，如防止侵蚀、洪水、海平面上升，以及为濒危、特有或迁徙物种提供专门的栖息地。前冲沙丘和向陆地迁移的抛物面沙丘在许多沿岸沙丘环境中发挥着重要作用，它们与内陆沙的输送、养分供应和地貌扰动过程有关，形成了生态异质性。然而，随着全球沿海沙丘越来越多地被植被所稳定，其生态复原力和功能也在下降，因此出现了一些人为干预措施，如清除入侵物种和挖掘前沙丘缺口，以模拟和恢复维持沙丘形态动力学以及海滩和内陆沙丘之间陆上沉积物运输所需的关键风化过程。本研究采用计算流体动力学（CFD）建模，研究了在不同宽度、坡度和平面形状（矩形与梯形）的理想前沙丘缺口内，垂直和倾斜入射风向的风流动力学和输沙潜力的关键控制因素。与类似工程缺口的经验研究结果相比，我们的研究结果表明，缺口宽度对挖掘缺口 "槽 "中的剪切速度有显著影响，较窄的缺口（25 米宽）可提高风流加速度和内陆沉积物迁移潜力。整个切口剪切速度的空间模式对入射风向也很敏感，当风向与切口方向平行时，剪切速度最大，因此内陆泥沙输运潜力也最大。在切口的叶片上，斜风时的剪切速度和输沙潜力最大。我们的研究结果表明，与盛行风向一致的相对较窄的凹口（如 25 米，而不是 50 米或 100 米），为将沉积物从海滩输送到后面的沙丘创造了最有利的条件。这些发现强调了缺口设计在沿海沙丘恢复中的重要性，为优化旨在维持从海滩到沙丘腹地的风化沉积物迁移的干预措施提供了重要启示。

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引用次数: 0

Physical modelling study on wave damping induced by an idealized floating kelp farm 理想化浮动海藻养殖场引起的波浪阻尼物理模型研究

IF 4.2 2区工程技术 Q1 ENGINEERING, CIVIL

Coastal Engineering

Pub Date : 2024-10-25 DOI: 10.1016/j.coastaleng.2024.104648

Filipe Miranda , Diogo Mendes , José Miguel Castro , Paulo Rosa-Santos , Francisco Taveira-Pinto , Tiago Fazeres-Ferradosa

A physical modelling study was carried out to investigate random wave damping promoted by an idealized floating kelp farm. The experimental conditions spanned intermediate water depths and both linear and nonlinear water waves. Unlike previous studies of wave damping promoted by vegetation, the floating kelp farm was placed close to the water surface with a ratio between vegetation height and water depth close to 0.25. The wave transmission coefficient induced by the floating kelp farm ranged between 0.56 and 0.96. This coefficient decreased for longer floating kelp farms and it was a function of the ratio between kelp farm length and incident wavelength and of the relative wave depth. Spectral analysis showed that wave damping was not frequency-dependent for wave frequencies close to the peak frequency. The wave transmission coefficients of a floating kelp farm with about 100 culture lines and with an extension of approximately 200 m were similar to those of submerged detached breakwaters with a relative crest freeboard smaller than −0.4. Furthermore, the bulk drag coefficient of near-surface idealized floating kelp farms can be modelled as a function of the Keulegan-Carpenter number. This study highlights the potential viability of nature-based solutions such as floating kelp farms for coastal protection.

为研究理想化浮动海藻养殖场所产生的随机波浪阻尼，进行了一项物理建模研究。实验条件跨越了中间水深以及线性和非线性水波。与以往研究植被对波浪的阻尼作用不同的是，浮动海藻养殖场靠近水面，植被高度与水深之比接近 0.25。浮动海藻养殖场引起的波浪传播系数介于 0.56 和 0.96 之间。浮动海藻养殖场越长，该系数越小，它是海藻养殖场长度与入射波长之比以及相对波深的函数。频谱分析表明，在波峰频率附近，波浪阻尼与频率无关。约有 100 条养殖线、延伸长度约为 200 米的浮动海藻养殖场的波浪传播系数与相对波峰自由板小于-0.4 的水下分离式防波堤的波浪传播系数相似。此外，近水面理想化浮动海藻养殖场的体积阻力系数可模拟为 Keulegan-Carpenter 数的函数。这项研究强调了浮动海藻养殖场等基于自然的海岸保护解决方案的潜在可行性。

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引用次数: 0

Structural and hydrodynamic modelling of the probability of breakage of branching and plate coral colonies 分枝珊瑚和板状珊瑚群断裂概率的结构和流体力学模型

IF 4.2 2区工程技术 Q1 ENGINEERING, CIVIL

Coastal Engineering

Pub Date : 2024-10-24 DOI: 10.1016/j.coastaleng.2024.104647

Wen Deng , Tania Kenyon , Karen Eigeland , David P. Callaghan , Tom E. Baldock

Climate change is amplifying the intensity of severe weather events, with coastal regions such as coral reefs facing heightened vulnerability to cyclonic wave forces. Structural models to predict bending stress and breakage of corals have been developed for coral colonies to enhance comprehension and prediction of the effects of hydrodynamic disturbances on coral reefs. However, there is scope for improving these predictions by evolving the methodology for quantifying complicated and variable coral morphologies. This study aims to predict breakage thresholds for two of the most prevalent coral morphologies: branching and plate corals (using Acropora muricata and Acropora hyacinthus as study species). Laboratory and field measurements were taken to assess coral morphologies and material characteristics. Morphological features of 47 branching colonies and 100 plate colonies were surveyed at the study site (Heron Reef, southern GBR) and the tensile strength of 80 coral samples was obtained by in situ and laboratory testing. Three-dimensional structural models of branching and plate coral colonies were developed, encompassing multiple coral colonies with varying morphological patterns from relatively shallow (5–7 m) to deep (9–12 m) zones. Model results were calibrated and verified with existing data, revealing that velocity thresholds of 1.7 m/s and 5.0 m/s would destroy 90% of the simulated branching coral structures growing in the deep and shallow parts of the forereef zone, respectively. In contrast, the plate corals have sufficient margins of safety even in extreme flow conditions (7 m/s). Additionally, skeletal strength and structural performance were adjusted based on varying degrees of bioerosion inside the coral skeleton. A higher probability of breakage was observed as the extent of bioerosion increased. The laboratory experiments of hydrodynamic loads on coral colony show that the sheltering effect due to one or two neighbouring colonies in the upwave direction is negligible. These models can be easily adjusted to provide predictions for other coral species, shapes, levels of bioerosion, and locations (e.g., sheltered or exposed areas). Comprehensive predictions about the level of expected damage and rubble generation in different areas can be used in reef management planning and restoration prioritization.

气候变化正在加大恶劣天气事件的强度，珊瑚礁等沿海地区更容易受到气旋波的影响。为了更好地理解和预测水动力扰动对珊瑚礁的影响，已经为珊瑚群建立了预测弯曲应力和珊瑚破损的结构模型。然而，通过改进量化复杂多变的珊瑚形态的方法，这些预测还有改进的余地。本研究旨在预测两种最普遍的珊瑚形态：枝状珊瑚和板状珊瑚（以 Acropora muricata 和 Acropora hyacinthus 为研究物种）的断裂阈值。通过实验室和实地测量来评估珊瑚的形态和材料特征。在研究地点（英国大堡礁南部的苍鹭礁）调查了 47 个分支珊瑚群和 100 个板状珊瑚群的形态特征，并通过现场和实验室测试获得了 80 个珊瑚样本的抗拉强度。建立了分支珊瑚群和板珊瑚群的三维结构模型，包括从相对较浅（5-7 米）到较深（9-12 米）区域形态各异的多个珊瑚群。根据现有数据对模型结果进行了校准和验证，结果表明，1.7 米/秒和 5.0 米/秒的速度阈值将分别摧毁 90% 生长在前礁区深部和浅部的模拟分支珊瑚结构。相比之下，板珊瑚即使在极端流速条件下（7 米/秒）也有足够的安全系数。此外，根据珊瑚骨架内部不同程度的生物侵蚀，对骨架强度和结构性能进行了调整。随着生物侵蚀程度的增加，珊瑚断裂的几率也随之增加。对珊瑚群的流体动力负荷的实验室实验表明，在上升波方向上，一个或两个相邻珊瑚群的遮蔽效应可以忽略不计。这些模型可以很容易地进行调整，以便为其他珊瑚物种、形状、生物侵蚀程度和地点（如遮蔽区或暴露区）提供预测。对不同区域的预期破坏和碎石产生水平的综合预测，可用于珊瑚礁管理规划和确定修复的优先次序。

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引用次数: 0

Satellite-derived bathymetry using Sentinel-2 in mesotidal coasts 利用哨兵-2 号卫星在潮间带海岸进行卫星水深测量

IF 4.2 2区工程技术 Q1 ENGINEERING, CIVIL

Coastal Engineering

Pub Date : 2024-10-23 DOI: 10.1016/j.coastaleng.2024.104644

S.P. Viaña-Borja , R. González-Villanueva , I. Alejo , R.P. Stumpf , G. Navarro , I. Caballero

Coastal zones are strategic environments of high socioeconomic, political, and ecological value, with over half of the world's population residing within 200 km of the coast. This proximity highlights their vulnerability to extreme events, which are exacerbated by global changes, leading to significant coastal impacts such as erosion, flooding, and ecosystem services deterioration. Consequently, efficient and operational methodologies for continuous monitoring are urgently needed to face these challenges. Bathymetric data are essential for understanding coastal dynamics, yet traditional data collection methods are often constrained by logistical challenges and high costs. Spaceborne remote sensing techniques offer significant advantages over traditional ground-based methods, particularly in terms of cost-effectiveness and operational efficiency. Over the last half-century, different Satellite-derived bathymetry (SDB) methodologies have been developed; however, challenges still persist. In this research, we applied a robust SDB methodology to three different study sites: Cíes Islands, Baiona Bay, and Vao beach within the Ría de Vigo, Galicia (NW Spain). These areas offer diverse and complex mesotidal environments to test for the very first time the methodology's efficacy. SDB was retrieved with a median absolute error (MedAE) ranging from 0.35 m to 1.55 m for depths up to 14 m. Results with different data source were evaluated, obtaining MedAE for nautical charts ranging from 0.46 m to 1.55 m. The precision between the data sources were quite close. In addition, multi-image composite was generated using images coinciding with both low tide (LT) and high tide (HT) conditions across the three zones. The lowest MedAE values were consistently obtained in images classified as LT (0.46 m) corresponding to Vao area. The results highlight the potential of nautical charts as a reliable source of calibration data for SDB, confirm the effectiveness of multi-image and switching models to correct artifacts and turbidity, considering tidal effects, improving single image approaches, and leverage visible bands for precise depth retrieval under varying conditions.

沿海地区是具有高度社会经济、政治和生态价值的战略环境，全球一半以上的人口居住在距海岸 200 公里以内的地区。这种邻近性凸显了它们在极端事件面前的脆弱性，而全球变化又加剧了这种脆弱性，导致侵蚀、洪水和生态系统服务退化等重大沿海影响。因此，迫切需要高效、可操作的持续监测方法来应对这些挑战。水深数据对了解沿岸动态至关重要，但传统的数据收集方法往往受到后勤挑战和高成本的制约。与传统的地面方法相比，空间遥感技术具有明显的优势，特别是在成本效益和作业效率方面。在过去的半个世纪中，已经开发出了不同的卫星水深测量（SDB）方法，但挑战依然存在。在这项研究中，我们在三个不同的研究地点应用了强大的 SDB 方法：这三个不同的研究地点分别是：西班牙西北部加利西亚维哥河内的 Cíes 群岛、Baiona 海湾和 Vao 海滩。这些地区提供了多样而复杂的潮间带环境，首次检验了该方法的有效性。对不同数据源的结果进行了评估，海图的中位绝对误差（MedAE）为 0.46 米至 1.55 米。此外，利用三个区域的低潮（LT）和高潮（HT）条件下的图像生成了多图像合成。与瓦澳地区相对应的被归类为 LT（0.46 米）的图像的 MedAE 值一直最低。这些结果凸显了海图作为 SDB 校准数据可靠来源的潜力，证实了多图像和切换模型在校正伪影和浊度、考虑潮汐效应、改进单图像方法以及利用可见光波段在不同条件下进行精确深度检索方面的有效性。

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引用次数: 0

Experiment study on vortex evolution process and vorticity distribution in wave boundary layer flow over a rippled bed 波纹床面波浪边界层流涡旋演变过程及涡度分布试验研究

IF 4.2 2区工程技术 Q1 ENGINEERING, CIVIL

Coastal Engineering

Pub Date : 2024-10-23 DOI: 10.1016/j.coastaleng.2024.104643

Shouqian Li , Shihuan Zhou , Yongjun Lu , Rui Hu , Wei Huang , J.A. Roelvink

Vortex over rippled bed acts as the main driving force for sediment transport under wave dynamics. Hydrodynamic experiments are carried out under matching conditions of wave dynamics and bed ripples, to reveal the vortex evolution process and vorticity distribution. The results indicate that the vortex body around the ripples experiences the evolution process of clockwise vortex formation, clockwise vortex detachment and dissipation, counterclockwise vortex formation, and counterclockwise vortex detachment and dissipation. Moreover, the vorticity at the ripple crest is proportional to U_w,rms/λ and η/λ, where U_w,rms represents the bottom velocity under wave action, λ represents the ripple length and η represents the ripple height. The vertical distribution of dimensionless vorticity depends on η. As η grows, the vorticity increases in the upper part and the vertical distribution of dimensionless vorticity becomes uniform. The circulation of the vortices is proportional to U_w,rms and η. The proposed expression for the vorticity at ripple crest, dimensionless vertical distribution of vorticity and circulation of the vortices all agrees well with the measured values. These findings lay the foundation for the study of the bottom sediment concentration.

波纹床面涡旋是波浪动力学条件下泥沙输运的主要驱动力。在波浪动力学和波纹床匹配条件下进行了水动力学实验，以揭示涡旋的演变过程和涡度分布。结果表明，波纹周围的涡体经历了顺时针涡体形成、顺时针涡体脱离和消散、逆时针涡体形成、逆时针涡体脱离和消散的演变过程。此外，波纹波峰处的涡度与 Uw,rms/λ 和 η/λ 成正比，其中 Uw,rms 表示波浪作用下的海底速度，λ 表示波纹长度，η 表示波纹高度。无量纲涡度的垂直分布取决于 η。随着 η 的增大，上部的涡度增加，无量纲涡度的垂直分布变得均匀。涡的环流与 Uw,rms 和 η 成正比。所提出的波纹波峰处涡度、无量纲涡度垂直分布和涡旋环流的表达式与测量值非常吻合。这些发现为研究底泥浓度奠定了基础。

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引用次数: 0

An enhanced model for an extreme wave impacting a vertical cylinder 冲击垂直圆柱体的极端波浪增强模型

IF 4.2 2区工程技术 Q1 ENGINEERING, CIVIL

Coastal Engineering

Pub Date : 2024-10-11 DOI: 10.1016/j.coastaleng.2024.104630

Bing Tai , Yuxiang Ma , Guohai Dong , Chan Ghee Koh , Tianning Tang , Marc Perlin

The interaction between extreme waves and a vertical cylinder is a complex process due to the intricate impact physics, three-dimensional effects, and unique characteristics of breaking waves. To improve wave force predictions, an enhanced model based on a finite-water-extent slamming theory that incorporates wave profiles is proposed. In contrast to the infinite-water-extent assumption in typical wave slamming theories, a finite volume of water with dual free surfaces is used, which better captures the wave's boundary conditions. Strip theory and potential flow theory are adopted to calculate sectional wave forces on the cylinder by solving the governing and boundary equations. The wave profiles, which provide the boundary conditions, result in a more realistic distribution of sectional forces than the often-assumed uniform distribution. Comparison with experimental data shows that the proposed model indeed provides more accurate wave force predictions and exhibits a gradual rise in impact force instead of an abrupt change observed in commonly used models.

由于错综复杂的冲击物理、三维效应和破浪的独特特征，极端波浪与垂直圆柱体之间的相互作用是一个复杂的过程。为了改进波力预测，我们提出了一个基于有限水程撞击理论的增强模型，其中包含波浪剖面。与典型坍波理论中的无限水程假设不同，该模型使用了具有双自由表面的有限水体，从而更好地捕捉了波浪的边界条件。采用带状理论和势流理论，通过求解控制方程和边界方程来计算圆柱体上的截面波力。波浪剖面提供了边界条件，使截面力的分布比通常假定的均匀分布更符合实际情况。与实验数据的比较表明，所提出的模型确实能提供更准确的波力预测，而且冲击力呈逐渐上升趋势，而不是常用模型中观察到的突然变化。

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引用次数: 0

Subaerial landslide-induced waves investigated with an adaptively mesh refined multiphase granular flow model 利用自适应网格细化多相颗粒流模型研究地下滑坡引发的波浪

IF 4.2 2区工程技术 Q1 ENGINEERING, CIVIL

Coastal Engineering

Pub Date : 2024-10-11 DOI: 10.1016/j.coastaleng.2024.104628

Novan Tofany , Arnida L. Latifah

Impulsive waves generated by subaerial landslides pose a significant threat to coastal or enclosed basin environments. However, simulating the intricate mechanisms involved is challenging due to the multiphase nature of the process, involving air, water, and granular materials interactions. While multiphase computational fluid dynamics (CFD) models offer realistic physics for improved simulations of landslide-induced waves, their high computational cost restricts their use to small-scale laboratory cases or domains. This study presents a multi-variable adaptive mesh refinement (AMR) approach integrated into a multiphase-CFD granular flow model to simulate subaerial landslide-induced wave phenomena. The AMR integration achieves dynamically evolving mesh resolutions in key areas of interest, significantly reducing the total cell count and mitigating computational overhead. The model’s performance is assessed across three laboratory-scale scenarios varying in landslide masses, particle sizes, water depths, and domain sizes. Results demonstrate that AMR maintains static-mesh model accuracy while improving computational efficiency, particularly in high cell count scenarios. Key findings highlight the AMR-enhanced model’s ability to capture both landslide and wave dynamics, showing grid-independence behavior and substantial reduction in computational time. The study emphasizes selecting appropriate AMR parameters, such as the refinement interval, to balance model accuracy and computational efficiency. Additionally, the detailed analysis of landslide dynamics reveals critical influences on wave generation, emphasizing the role of landslide deformation and water penetration in the leading and secondary wave characteristics. Several limitations and computational issues arising from AMR implementation are identified, with recommendations for future improvements. Overall, this study provides valuable insights into the potential of AMR-enhanced multiphase-CFD models for accurately and efficiently simulating landslide-induced waves, offering significant implications for coastal engineering applications.

陆下滑坡产生的冲击波对沿海或封闭盆地环境构成重大威胁。然而，由于该过程具有多相性，涉及空气、水和颗粒材料的相互作用，模拟其中的复杂机制具有挑战性。虽然多相计算流体动力学（CFD）模型为改进滑坡诱发波的模拟提供了逼真的物理原理，但其高昂的计算成本限制了其在小规模实验室案例或领域中的应用。本研究提出了一种将多变量自适应网格细化（AMR）方法集成到多相-CFD 颗粒流模型中的方法，用于模拟陆下滑坡诱发的波浪现象。AMR 集成实现了关键区域网格分辨率的动态演化，大大减少了单元总数，降低了计算开销。该模型的性能在三个实验室规模的场景中进行了评估，这些场景的滑坡质量、颗粒大小、水深和域大小各不相同。结果表明，AMR 保持了静态网格模型的准确性，同时提高了计算效率，尤其是在单元数较多的情况下。主要发现强调了 AMR 增强模型捕捉滑坡和波浪动态的能力，显示出与网格无关的行为，并大大减少了计算时间。研究强调选择适当的 AMR 参数，如细化间隔，以平衡模型精度和计算效率。此外，对滑坡动力学的详细分析揭示了波浪产生的关键影响因素，强调了滑坡变形和水渗透在前波和次波特征中的作用。研究指出了 AMR 实施过程中出现的一些局限性和计算问题，并对未来的改进提出了建议。总之，这项研究为 AMR 增强型多相 CFD 模型准确、高效地模拟滑坡引起的波浪的潜力提供了有价值的见解，对海岸工程应用具有重要意义。

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引用次数: 0

An adaptive internal mass source wave-maker for short wave generation 用于产生短波的自适应内部质量源造浪机

IF 4.2 2区工程技术 Q1 ENGINEERING, CIVIL

Coastal Engineering

Pub Date : 2024-10-10 DOI: 10.1016/j.coastaleng.2024.104629

Huiran Liu, Pengzhi Lin

The mass source wave-maker is commonly employed for generating water waves in numerical simulations, during which a correct amount of mass is introduced or subtracted from the internal flow region to produce target waves. The method has proven to be effective in producing waves in shallow and intermediate water depths, while its efficiency is declined for short wave generation. The main reason for this efficiency declination is that the internal mass source in deeper water region is not effective to generate short waves with their motions primarily on water surface. In order to overcome this shortcoming, many of the previous numerical treatments have introduced various enhancement factors into the source functions, which are empirically obtained and also violate the law of mass conservation. In this study, we develop a new adaptive internal wave-maker model that can be self-adjusted to suit different wave conditions. The line source starts from the bottom and extends to the computational cell right beneath free surface at each time step. The depth dependent weighting coefficient is introduced to the source function based on the linear wave theory for each wave component. No empirical coefficients are necessary, and the mass conservation is strictly and explicitly enforced. In principle, the method can be applied to all types of linear waves in the entire range of kh. The numerical experiments show that the present method can produce very good results for linear waves with kh up to 16.11, adequate for most of wave conditions in coastal engineering. For generation of fifth-order Stokes waves, the method can be extended straightforwardly for each of five wave components. For irregular waves composed of many linear wave components, different weighting coefficients can be readily calculated for each of them, respectively. As a result, the new model can generate irregular waves with overall better performance of reproducing wave spectrum, whose high-frequency part has been underestimated by previous methods. The numerical experiments also show that the new model can produce better results for focused waves where many linear waves of different frequencies start from the same point with specific phase angles, due to its capability of generating shorter wave components.

在数值模拟中，通常采用质量源造浪器来产生水波，在此过程中，从内部流动区域引入或减去一定量的质量，以产生目标波浪。事实证明，该方法在产生浅水和中层水深的波浪时非常有效，但在产生短波时效率却有所下降。效率下降的主要原因是深水区的内部质量源不能有效地产生主要在水面运动的短波。为了克服这一缺陷，以前的许多数值处理方法都在源函数中引入了各种增强因子，这些因子都是根据经验得到的，同时也违反了质量守恒定律。在本研究中，我们开发了一种新的自适应内部造浪模型，可根据不同的波浪条件进行自我调整。线源从底部开始，在每个时间步扩展到自由表面下的计算单元。根据线性波浪理论，为每个波浪分量的源函数引入了与深度相关的加权系数。不需要经验系数，质量守恒得到了严格和明确的执行。原则上，该方法可适用于整个 kh 范围内的所有类型的线性波。数值实验表明，本方法可以对 kh 最大为 16.11 的线性波产生很好的结果，足以满足海岸工程中的大多数波浪条件。对于五阶斯托克斯波的产生，该方法可以直接扩展到五个波浪分量中的每一个。对于由多个线性波浪分量组成的不规则波浪，可以很容易地分别计算出每个波浪分量的不同加权系数。因此，新模型生成的不规则波在再现波谱方面具有更好的整体性能，而以往的方法低估了波谱的高频部分。数值实验还表明，由于新模型能够产生较短的波分量，因此对于许多不同频率的线性波以特定相位角从同一点出发的聚焦波，新模型能够产生更好的结果。

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引用次数: 0