Journal of Waterway, Port, Coastal, and Ocean Engineering

Investigation of breaking and undular tidal bores is a challenging problem in river mouths as fluid flows upstream, where significant bed erosion and scour take place under the bore. In this study, smoothed particle hydrodynamics (SPH) was used to simulate the breaking and undular tidal bores on a movable bed. To model the bores, a moving gate was used to block a steady uniform flow in a channel, and bores were consequently generated as a positive surge and propagated upstream. First, results were presented for the breaking and undular bores on a flat bed, looking carefully at velocity and surface profiles, which were compared with available experimental data. Then, the breaking and undular bores were tested in a channel with a movable bed using a previous experimental study of particle motion. The authors show the morphology changes of the bed under the breaking and undular bore. The results show that the SPH method can be successfully used to investigate the dynamics of the tidal bore and its effects on a movable bed.

Two in situ geotechnical surveys were undertaken in Sydney Harbour, Nova Scotia, Canada, following the dredging and relocation of 4.2 million m³ of sediment from the shipping channel during the fall and winter of late 2011 and early 2012. The surveys were conducted 9 and 18 months after dredging using a portable, free-fall penetrometer. A new method for rapid assessment of the in situ state of sediment consolidation from free-fall penetrometer data was developed and applied to identify areas of sediment erosion and deposition. Results 9 months after dredging showed an initial accumulation of dredge-resuspended sediments. Eighteen months after dredging, stability, and evidence of consolidation or continued accumulation was found at more than 92% of the 39 sampled locations examined. Evidence of erosion was observed at only 3 locations. The general pattern of sediment stability observed is consistent with the historically low energy and sedimentation environment of the inner regions of Sydney Harbour.

A data-driven prediction model using numerical solutions is proposed for forecasting wave heights along shipping routes during hurricanes. The developed model can be used to determine the wave heights on a ship’s trajectory, considering a short time step of a ship’s operation. This research used an artificial neural network (ANN) multilayer perceptron model (ANN-based) to build a data-driven prediction model. A quadtree-adaptive model was used as the numerical simulation–based model (NUM-based). The proposed NUM-ANN model is an ANN-based prediction model that incorporates precomputed numerical solutions to determine the wave heights at sample points on the shipping line where buoy measures are absent. The NUM-ANN model is highly efficient because the input–output patterns used to formulate it can be generated in advance through numerical models. A shipping line through the Caribbean Sea and the Gulf of Mexico was used for simulation. The 2005 Category 5 hurricanes Katrina and Rita were used for testing. Three buoys and three sample points on the ship trajectory were applied for modeling the wave heights. The results revealed that (1) for shipping-line buoys, the predictions made using the NUM-based and ANN-based models are satisfactorily consistent with the observed data; and (2) for the sample points, the predictions made using the NUM-ANN model are highly consistent with simulations made using the NUM-based model. Therefore, ANN-based prediction models can be regarded as reliable, and the NUM-ANN model can be effectively used in the real-time forecast of wave heights.

Among the numerous wave-energy converters (WECs), the oscillating water column (OWC), which runs on the concept of capturing energy from the rise and fall of the water column in a closed chamber resulting from wave motion, has become quite popular. The compressed water column in the chamber advances an air stream that can drive a turbine coupled to electric generators. The present study aimed to investigate the influence of the projecting sidewalls, or so-called harbor walls, of an OWC on its energy-efficiency characteristics. The design and optimization of the harbor wall’s projecting length and its inclination are as important as the hydrodynamics of waves inside the chamber, apart from the characteristics of the air vent and the turbine parameters, which play a critical part in the performance of these devices. The objective of the present study was to optimally convert the incident wave-energy into pneumatic power by analyzing the influence of projecting sidewalls and optimizing the length and inclination (opening angle) of the walls. The projecting length was varied in terms of the ratio of the harbor wall length (c) to the breadth of the OWC (b) (c/b = 1, 1.5, and 2). The inclination of the harbor wall was varied in the range of (π/2, 7π/8) at an interval of π/8 with respect to the front lip wall of the OWC.

Assuming that an ideal liquid has irrotational, incompressible, and inviscid flows, a mathematical model is presented to efficiently and simply study liquid sloshing problems under longitudinal excitation in horizontal cylindrical containers with complex baffles. A semianalytical scaled boundary finite-element method (SBFEM) is combined with the zoning technique to solve the liquid sloshing problem. This method can significantly increase the efficiency and accuracy of the calculation using few nodes. Using scaled boundary coordinates with both radial and circumferential directions, the analytical solution in the radial direction can be obtained through approximation in the circumferential direction via a discretization technique similar to that used in the FEM. Thus, the entire calculation domain can be analyzed based on the problem boundary. Continued-fraction expansion is applied to build the eigenvalue problem, and the interior eigenvectors are solved by using asymptotic expansion in detail. Based on the previously mentioned decomposition and eigenvalue problem, the corresponding sloshing mass and motion equations are proposed by an efficient methodology. The simplicity and efficiency of SBFEM applied to sloshing problems with different baffles are obtained through numerical examples. This paper investigates the effects of the arrangement and length of different baffles and liquid fill levels on the sloshing frequencies, modes, and response. The conclusions illustrate that SBFEM can easily and semianalytically achieve good results for complex sloshing problems with singularity and complex geometry by placing the scaling centers at the tip of the baffles with very few degrees of freedom.

This work reports on an experimental investigation focused on the hydro-morphodynamic response of a submerged reef made of geotextile sand containers (GSCs). Reflection and transmission across the barrier were evaluated focusing on the effects of (1) placement of the GSC, (2) filling sand, and (3) saturation of the structure. Moreover, the hydraulic stability of the GSC reef and the scour at the offshore toe were analyzed and compared with other literature studies. Results showed that a stability curve separates the stable condition from the incipient motion. The scour follows the time evolution of traditional structures, but its maximum value is deeper than that shown at the toe of a rubble-mound structure.

Ports are located in areas often susceptible to storm surge and flooding from severe storms as well as the potential impacts of climate change, such as sea level rise. Although there is a significant body of work addressing the vulnerability of ports subjected to earthquakes, models that support risk assessment of ports subjected to storm surge and waves from coastal hazards, including hurricanes, are scarce. This study presents a methodology for fragility analysis of wharf/pier structures typical in port facilities that are subjected to hurricane-induced storm surge and wave loading. Such models enable future risk assessment of these structures when exposed to current or projected storm conditions. The framework presented first utilizes Latin hypercube sampling within a Monte Carlo simulation to estimate uncertain vertical and horizontal demands from surge and wave loading, along with uncertain capacities associated with uplift, shear, and flexural failure. Fragility surfaces are then generated, expressing failure probability given wave height and relative surge elevation. Furthermore, stepwise logistic regression is applied to derive the parameterized deck–pile connection fragility functions for ready application in regional risk assessment. The proposed approach is applied to four alternative deck–pile connections typically found in wharves/piers: a full moment connection with dowels inside of the compression zone, a full moment connection with dowels outside of the compression zone, a partial moment connection with dowels inside of the compression zone, and a partial moment connection with dowels outside of the compression zone. The results suggest that the dominant structural failure mode for all of the examined cases is uplift. Furthermore, the partial moment connections are more vulnerable to storm surge and waves compared to full moment connections. Although providing sufficient clearance is a preferred method for port safety, it is not always possible to keep the wharf/pier deck sufficiently elevated above the sea level. Given the criticality of these structures to maintain port operations posthazard event, this paper offers a method for efficiently estimating their hurricane fragility that can be extended in the future to a portfolio of portstructures and applied for current hazard conditions or future scenarios including the effects of climate change.

Numerical simulations are often used to predict the deformation of waves and their impact on structures in harbors and access channels. An underprediction of these waves could lead to structural failure or ship accidents, so accurate numerical models should be capable of capturing the complex physical processes correctly. In this contribution, the authors consider wave penetration into a harbor with a complex bathymetry from an access channel using numerical simulations with wave models in a software program. The wave models were derived based on consistent modeling using a variational principle for water waves to produce the dynamic equations in Hamiltonian form. By approximating the Hamiltonian, the so-called analytic Boussinesq (AB) model was used and discretized into a global spatial-spectral numerical method. Numerical results compared with laboratory experiments show better performance than in other publications on the same application.

Shoaling in intermediate and shallow waters is a major process that occurs as the water wave travels toward the shore from deep waters. Evaluation of the appropriate shoaling coefficient (K_s) is essential in understanding the nearshore energy distribution and surf-zone dynamics. The value of K_s is underestimated using linear wave theory in shallow waters. The present work focused on the investigation of the shoaling coefficient through wave-flume experiments and numerical simulations. Furthermore, comparisons were made with nonlinear theories to bring out the range of applicability of theories. A submerged ramp was used in the wave-flume experiments to mimic the shoaling process. The nonlinearity in the unshoaled and shoaled-wave profiles were brought out using skewness and kurtosis. It was found that Cokelet’s nonlinear theory agrees well with the measurements and computations. The comparative analysis of the experimental measurements with the numerical simulations suggests that the numerical model is a powerful tool to reproduce the wave-transformation process over sloping beds.

The Godavari is an important tropical monsoonal river located along the east coast of India. The Gautami-Godavari is one of the two major estuarine branches of the Godavari River bifurcated by a low dam at Dowlaiswaram. The study focused primarily on the dam-controlled freshwater fluxes using extensive field data on hydrodynamics and numerical modeling of tidal currents. A two-dimensional hydrodynamic model was used to simulate the tidal circulation for the period 2009–2010 by forcing it with predicted tides, river discharge from the dam, and rainfall. The model produced accurate results with negligible bias in the current speed during zero-discharge conditions and a bias of approximately 0.08 m·s^{− 1} during moderate- and high-discharge conditions. The observations and numerical modeling, suggest that the estuary is dominated by tides during the dry season (December–May) and by high freshwater fluxes during the wet season (June–November) associated with the Indian Southwest Monsoon (ISM). During the ISM, the salinity and stratification were found to be highly variable and were mostly controlled by the dam’s discharge. The characteristics of the estuary were transformed from a salt-wedge type in February to a river type in November, instead of during the peak monsoon season (August), indicating extensive variability in the dynamics linked to the freshwater fluxes from the dam. From the hourly observations of salinity at Yanam station over a tidal cycle, the presence of saltwater intrusion was observed even during high river discharge in the flood (currents moving from sea to the estuary) period. The magnitude of the currents strongly varied between 0.2 and 0.8 m·s⁻¹ during different tidal phases. It was found that the flushing times were mostly controlled by river discharge during the wet season and by the tides during the dry season.

The devastating April 16, 2016, Pedernales, Ecuador, M_w 7.8 earthquake was among a sequence of ruptures that occurred along the seismically segmented North Andean subduction zone. It caused 700 fatalities, and more than 7,000 people were injured. The magnitude and location of it were similar to those of the May 14, 1942, earthquake, relaxing some of the strain accumulation that had built up over more than 74 years. A weak tsunami was detected in four nearby tide gauges. Analysis of the records provides useful information on the earthquake and tsunami. An estimate of 6.5 cm of coseismic subsidence was reported at the Bahía de Caráquez and Manta locations, while no movement was detected at Esmeraldas and La Libertad. The analysis also supports the existence of two major seismic asperities and a weaker one farther south. A tsunami resonance occurred at the Bay of Salinas, the location of La Libertad, even though the bay is very wide. It was fortunate that it was inconsequential, this time, because the incoming wave was substantially dissipated.

A new methodology is proposed for the generation of breaking focused waves in computational fluid dynamics (CFD) simulations. The application of the methodology is illustrated for a numerical flume with a piston-type wavemaker built in the CFD model olaFlow. Accurate control over the spectral characteristics of the wave group near the inlet and the location of focus/breaking are achieved through empirical corrections in the input signal. Known issues related to the spatial and temporal downshift of the focal location for focusing wave groups are overcome. Focused wave groups are produced with a first- and second order-paddle motion, and the propagation of free and bound waves is validated against the experimental results. A very good overall degree of accordance is reported, which denotes that the proposed methodology can produce waves breaking at a focused location.

Multilayer nonhydrostatic models have gained popularity in the computation of ocean wave processes, but a recent attempt to make a connection to the Boussinesq-type approach raises some fundamental issues that require a rigorous assessment beyond the conventional framework of approximation. Such an endeavor is readily feasible for depth-integrated nonhydrostatic models because of the existence of an equivalent Boussinesq form. An examination of the governing equations shows that defining the nonhydrostatic pressure at layer interfaces for depth integration gives rise to a leading-order approximation of the dispersion relation distinct from the Taylor-series expansion. Introducing a parameterized nonhydrostatic pressure profile or increasing the number of layers is akin to retaining high-order terms in the Boussinesq-type equations with comparable rational function approximations of linear and nonlinear wave properties. Although both approaches converge to the exact solution at high order, the spatial derivatives in nonhydrostatic models always remain at first order. The simple numerical framework along with grid refinement techniques enable application of a single model over a wide range of spatial scales for practical application.