Full-scale experimental study on wave reflection and run-up at stepped revetments

: Wave runup and overtopping on inclined coastal structures and wave runup on beaches are reviewed together to examine the ranges of wave runup processes occurring on slopes of different inclinations. Laboratory experiments on regular wave runup and overtopping on coastal structures are reviewed first to provide historical perspec- tive. More recent laboratory experiments on irregular wave runup and overtopping on coastal structures are summarized to show the improved quantitative understanding due to the improved capabilities for irregular wave experiments. Field experiments on wave runup on beaches are then reviewed to discuss the possible dominance and causes of low frequency shoreline oscillations on gently sloping beaches. The recent development of time dependent numerical models is reviewed to indicate the rapid progress of the numerical capabilities of predicting irregular wave runup on inclined coastal structures and beaches. This review indicates that the improved quantitative understanding of irregular wave runup and overtopping on inclined coastal structures and irregular wave runup on beaches has essentially been limited to normally incident waves on coastal structures and beaches of alongshore uniformity. Future experimental and numerical studies are suggested in this review.

Wave runup and overtopping pose significant risk to coastal areas and need continuous monitoring to support disaster mitigation. We propose a real-time coastal monitoring system employing Light Detection and Ranging (lidar) technology. The system was tested at two beaches facing the Sea of Japan over two winter seasons. Both sites experienced heavy snow, rain, and steam fog, and the presence of coastal structures further complicated the accurate shoreline detection. The lidar-based measurements were validated by shoreline positions derived from videos taken by surveillance cameras synchronized with the lidar scanners. While the lidar-based shoreline positions tended to be slightly seaward, the runup height measurements showed strong agreement with the camera-based data. Root mean squared difference (RMSD) values of the runup heights were approximately 0.35 m at the gravel beach, where the wave runup heights reached 5 m several times. At the composite beach of sand and gravel, the RMSD values were below 0.2 m, with maximum runup heights reaching 2.5 m. The system also demonstrated the capability to detect wave overtopping at a seawall under severe storm conditions. The findings demonstrate that the proposed system can provide quantitative data on wave runup and overtopping, offering valuable support for coastal management.

In the interaction between waves and structures, the maximum wave run-up height on the surface of the structure and the wave field distribution around the cylinder are important factors to be considered in the design of marine structures. In this paper, the open source software OpenFOAM is used to simulate the wave run-up phenomenon of a truncated cylinder under regular waves by solving the Reynolds-averaged Navier–Stokes equation. The established numerical model is verified with the experimental data, and the good consistency demonstrates the accuracy in simulating the interaction between waves and fixed truncated cylinders. The numerical results show that the draft of the cylinder under regular waves has little effect on its maximum wave run-up height, but has a significant effect on the horizontal wave force. At the same wave steepness, the radial dimensionless run-up height increases with the increase of scattering parameters ka, where k is the wave number and a is the cylinder radius. The radial run-up height decreases gradually along the radial direction in the upstream, and increases gradually along the radial direction in the downstream.

Statistical characteristics of long waves nearshore

Simulating wave runup on an intermediate–reflective beach using a wave-resolving and a wave-averaged version of XBeach

An improved method for calculating the wave run-up on a vertical cylinder based on the velocity stagnation head theory

Wave run-up is an important phenomenon that should be considered in ocean structure design. In this study, the wave run-up of a surface-piercing circular cylinder was calculated in the time domain using the three-dimensional linear and fully nonlinear numerical wave tank (NWT) techniques. The NWT was based on the boundary element method and the mixed Eulerian and Lagrangian method. Stokes second-order waves were applied to evaluate the effect of the nonlinear waves on wave run-up, and an artificial damping zone was adopted to reduce the amount of reflected and re-reflected waves from the sidewall of the NWT. Parametric studies were conducted to determine the effect of wavelength, wave steepness, and the draft of the cylinder on the wave run-up of the cylinder. The maximum wave run-up value occurred at 0°, which was in front of the cylinder, and the minimum value occurred near the circumferential angle of 135°. As the diffraction parameter increased, the wave run-up increased up to 1.7 times the wave height. Furthermore, the wave run-up was 4% higher than the linear wave when the wave steepness was 1/35. In particular, the crest height of the wave run-up increased by 8%.

Hydrodynamic characteristics of a vertical wall with an immersed horizontal plate subjected to regular and random waves

On the accuracy of large-steepness regular wave generation, propagation and run-up on a cylinder

Tsunami wave inundations are still one of the most devastating natural disasters worldwide. Tsunamis striking a settlement frequently devastate much of its infrastructure. In instances where infrastructure withstands the tsunami’s actions, it acts as a flow resistance for the wave’s run-up, altering inundation dynamics and flow depth. Accurately predicting the complex dynamics of tsunami wave run-up in densely populated urban areas is paramount for informing effective evacuation protocols and conducting comprehensive hazard and risk assessments. In pursuit of improving wave run-up prediction capabilities, this study delves into the three-dimensional numerical modelling of wave run-up of non-breaking, long tsunami waves in urbanized areas. Leveraging insights from a physical experiment with pump-driven wave generation and idealized infrastructure, a novel pressure-based wave generation boundary condition is developed. The boundary condition achieves an average of 4.9% accuracy in replicating the water surface elevation from experiments. Additionally, it attains an average 1.5% precision in reproducing flow velocities, furthermore reproducing the spatial flow dynamics accurately. Physical experiment wave run-up is modelled with an average 6.9% deviation for both simulations with and without idealized infrastructure. 63.0% higher non-linearity waves than in the physical experiments are additionally investigated to highlight the boundary conditions capabilities of high non-linearity wave generation, change in run-up reduction for higher non-linearity waves for infrastructure interaction and furthermore in-depth flow field characteristics during tsunami inundation. Finally, the study highlights deviations from analytically calculated wave run-up, emphasizing the necessity for numerical and physical experimental evaluation for both high non-linearity waves and tsunami infrastructure interaction, ultimately fostering both resilience and preparedness against tsunami hazards.

Numerical modelling of wave transformation and runup over rough fringing reefs using VARANS equations

A numerical model of wave run-up, overtopping, and regeneration is presented. The model (called OTT) is based on the one-dimensional nonlinear shallow water equations on a sloping bed, including the effects of bed shear stress. These equation are solved using a finite-volume technique incorporating a Roe-type Riemann solver. The main advantage of this approach over previously used finite difference solvers is that no special shoreline-tracking algorithm is required, so that noncontiguous flows can easily be simulated. Hence, this model can be used to simulate the transmission of waves over water surface-piercing obstacles. The numerical scheme and boundary conditions are described, and several existing data sets used to test the ability of the model to simulate wave transformation, run-up, and overtopping. Experiments of random wave (unimodal and bimodal) overtopping, presented here for the first time, indicate that the model performs much better than empirical formulas in predicting average overtopping rates, and that it provides good estimates for the number of overtopping events. Experiments of overtopping of a sea wall by solitary wave are also presented, including measurements of wave regeneration in lee of the dike. The model does a reasonable job of reproducing the water depths on top of the dike, and performs well in simulating the initial height of the regenerated waves.

A 2D numerical model of wave run-up and overtopping

Surface roughness effect of vertical and sloped seawalls in incident random wave fields

Wave run-up is the vertical extent of wave up rushed on a structure. To describe wave run-up characteristic, we tend to relate to its maximum height. It was a common belief that the leading wave will usually reach the maximum run-up. However, It turns out that this is not always the case. Resonance is a phenomenon when the incident wave shares the same frequency as the natural frequency. In this article, the natural frequency of a semi-enclosed basin on a plane structure is derived using the variable separation technique. Next, the staggered conservative scheme is used to test these natural frequencies through simulations of wave run up on a plane structure. The result shows that when the incoming wave frequency is close to the natural frequency, the largest run-up height is not the leading wave, but the second, third, or fourth waves. This indicates the occurrence of resonance phenomena. Sensitivity analysis was applied to show the dependence of the maximum run-up height to the structure’s slope, as well as the incident wave frequency. Further, a physical simulation was conducted to examine whether the resonance phenomenon appears in the actual events.