Journal of Waterway, Port, Coastal, and Ocean Engineering

In this study, we discuss the diffraction of linear water waves by a cylindrical storage tank whose inner part contains a cylindrical pile and the outer part contains a coaxial thin hollow porous cylinder in finite ocean depth. Here we consider two cases: (i) an impermeable solid circular cylinder surrounded by an outer coaxial thin hollow porous cylinder of the same height extending from the free surface to the seabed; (ii) a similar structure fully placed atop an impermeable solid circular cylinder with the same radius as the outer cylinder. The fluid region is divided into two subdomains and the separation of variables technique is used to obtain the analytical expressions for the corresponding potentials in each region. The porous wall condition is used with respect to the thin porous wall. Appropriate matching conditions are applied at the interface of the fluid subdomains to obtain a system of linear equations for the unknown coefficients which is solved. By considering different sets of values of the radius and the porosity of the cylinder, the hydrodynamic force and wave run-up are evaluated. It is observed that the wave forces and wave run-up get reduced on the inner cylinder corresponding to higher radius ratio and lower porosity whereas the wave forces on the outer cylinder get reduced for higher porosity. A suitable combination of the parameter values of the cylinder is likely to bring down the wave forces to a large extent. Upon verification and validation of results for both models against available analytical result and experimental data, it may be considered beneficial to apply the present models to certain applications in ocean engineering.

This article introduces an effective flood control method in the downstream of a river through the optimal operation of a barrage that is connected with a sea. A new operating model for flood control of an estuary barrage that can comprehensively evaluate the intensive discharge through the floodgates at the estuary barrage during low tide and the flood propagation process in the downstream river system is proposed. The optimization method applied to the operating model of the barrage combines a one-dimensional hydrodynamic model to analyze the flood propagation process in river channels and a search algorithm based on an iterative method to organize the maximum discharge at the estuary barrage during the ebb tide periods. The proposed method was applied to the flood control of the Taedong River downstream in the Democratic People's Republic of Korea, and its effectiveness was shown and evaluated through modeling results. By imagining the downstream boundary of the river before and after the construction of the West Sea Barrage, the inundation simulation at the Taean gauging station in the downstream of the Taedong River for floods of different average recurrence interval (ARI) was achieved by employing the proposed method.

Dredged sediment is commonly placed as a submerged nearshore berm to nourish the beach or to dissipate high-energy waves, but the lifespan of such features is not easily predicted by existing methods. This paper presents a simple technique for generating order-of-magnitude estimates of the sediment transport rate of nearshore berms using offshore hindcast wave characteristics transformed to the nearshore. Total longshore transport for the entire nearshore region is calculated using eight published longshore transport equations (e.g., CERC equation and Kamphuis equation), which were evaluated for their relative performance. Because nearshore placements occupy only a portion of the cross-shore profile, the total longshore transport rate is scaled by an empirically-based fraction between 0 and 1, which is determined by the nearshore berm’s position in nondimensional space. The cross-shore transport rate is calculated independently using the near-bed orbital velocity from stream-function wave theory. The longshore and cross-shore transport rates are then superimposed to generate a total transport rate for the nearshore berm’s constructed footprint. The total transport rates were calculated at 11 historical nearshore berms and evaluated based on accuracy, inclusion of relevant coastal processes, and sensitivity to input parameters. The recommended total transport rate technique resulted in an average percent error magnitude of 72% and a maximum percent error magnitude of 167% at the historical placement locations. This technique is recommended for generating rapid, order-of-magnitude estimates of nearshore berm deflation rates for project design, particularly in scenarios when application of a full numerical model is prohibitive.

The main measure of response to aquatic oil spills is the mechanical containment and recovery from the water surface. The majority of containment booms are not effective when the relative current/tow speed exceeds approximately 1 knot. A research study was conducted to assess the performance of some existing booms and to propose improved and novel boom concepts for use in high-speed situations. Studied booms included conventional single-skirt and L-shaped booms, and boom systems involving screens and ramped skirts. The study included two-dimensional computational fluid dynamics simulations and physical modeling experiments. The computational modeling utilized the open-source OpenFOAM toolbox briefly validated prior to computational modeling of high-speed boom concepts. The physical modeling component was conducted in a 95-m-long and 2-m-wide wave-current flume. Despite some differences in the details of what was computationally and physically modeled, the boom performance and containment success were generally consistent. Among several studied boom concepts, ramped-boom and screen-boom systems were most promising for the containment of light and medium oils in relative speeds of 2–3 knots.

The resistance of commercial vessels in inland waterways is an essential and widely investigated problem. Depending on vessel and channel shape and size, many empirical equations were developed in the past to determine the resistance of vessels. In order to obtain an accurate relationship to predict the total resistance of inland vessels for variable channel and vessel dimensions, numerous model resistance tests with motor ships, push tows, and barge convoys were evaluated. If the speed of the vessel is limited to a defined economic speed, which is usually not exceeded in inland waterways, it is shown that the resistance from model tests of both ships and tows can be determined well by a resistance equation, which is based on a formula derived by van de Kaa for canals. A satisfactory agreement of the calculation results can be demonstrated for motor ships with measurements in field tests. It turns out that the adopted resistance equation of van de Kaa provides good results for inland vessels in a wide range of inland waterway dimensions.

The breaking wave interactions on a vertical wall with three different recurved parapets were examined in two different scales (1:1 and 1:8) to study the scale effects. A similar testing condition with that of the large scale was adopted to identify a method for scaling up the small-scale laboratory measurements that involve impact pressure or forces. In the present study, two approaches for scaling up the small-scale studies, namely the Froude and Cuomo methods are adopted. By comparing the scaled-up results from small-scale studies with large-scale studies using the two approaches, a combined approach was suggested to estimate the force by integrating the pressure. In the proposed approach (named Cuomo–Froude method), the Cuomo method was adopted in the impact zone, and the Froude method was adopted in the nonimpact region for upscaling the small-scale experiments. The proposed approach shows a reasonable comparison with large results for pulsating and impulsive breaking conditions with a vertical wall having a different exit angle. Finally, the paper concludes that the pressure impulse follows the same scale for wave impacts as pressure.

Vegetation on foreshores in close vicinity to sea dikes may prove beneficial as regulating ecosystem service in the context of coastal defense, dike safety, and flood protection by reducing loads on these defense structures. Predominantly, a decrease in wave heights and bottom shear stresses is hypothesized, which calls for an inclusion in design procedures of coastal defense structures. In contrast to heterogeneous and variable salt marsh vegetation, this study uses surrogate vegetation models for systematic hydraulic experiments in a wave flume, without modeling specific plant species a priori. Froude-scale experiments are performed in order to investigate the effect of salt marsh vegetation on the wave transformation processes on the foreshore and wave run-up at sea dikes. The effect of plant and wave properties on wave transmission, energy dissipation, and wave run-up at a 1:6 sloped smooth dike are presented and discussed, focusing on the wave–vegetation–structure interaction. Vegetated foreshores can contribute to wave attenuation, where an increasing relative vegetation height h_v/h results in decreased wave run-up on the dike by up to 16.5% at h_v/h = 1.0.

The state-of-the-art formulas for mean wave overtopping (q) assessment typically require wave conditions at the toe of the structure as input. However, for structures built either on land or in very shallow water, obtaining accurate estimates of wave height and period at the structure toe often proves difficult and requires the use of either physical modeling or high-resolution numerical wave models. Here, we follow Goda's method to establish an accurate prediction methodology for both vertical and sloping structures based entirely on deep-water characteristics—where the influence of the foreshore is captured by directly incorporating the foreshore slope and the relative water depth at the structure toe (h_toe/H_m0,deep). Findings show that q decreases exponentially with h_toe/H_m0,deep due to the decrease of the incident wave energy; however, the rate of reduction in q decreases for structures built on land or in extremely shallow water (h_toe/H_m0,deep ≤ 0.1) due to the increased influence of wave-induced setup and infragravity waves—which act as long-period fluctuations in mean water level—generated by nonlinear wave transformation over the foreshore.

This work presents a case study involving the numerical simulation of the unsteady boundary layer generated by the 2010 Chilean tsunami, as measured by field equipment in Monterey Bay, California, USA. A one-dimensional vertical (1DV) boundary layer model is utilized, solving Reynolds-averaged Navier–Stokes equations, coupled with two-equation k–ω turbulence closure. Local effects of convective acceleration (converging–diverging effects) on the boundary layer due to the sloping bed are likewise approximated. Four cases are considered involving simulation of: (1) the long tsunami-induced boundary layer flow in isolation, in combination with either (2) convective acceleration effects or (3) energetic short wind waves, and, finally, (4) all effects combined. Reasonable agreement with field measurements is achieved, with model results similarly showing that the tsunami-induced boundary layer in this case only spans a fraction of the local water depth. Systematic comparison of the various cases likewise elucidates the likely significance of both local converging–diverging effects, as well as interaction with the much shorter period wind waves, on the tsunami-generated boundary layer. In the latter case, analogy is drawn to well-known wave–current boundary layer interaction, with the boundary layer turbulence associated with the short wind waves inducing an effective wave roughness felt by the tsunami-induced flow, which effectively plays the role of the current.

The macrotidally influenced harbor of Dagebüll on the North Sea coast of Germany features a piled south jetty, for which provided constructive designs are investigated regarding their potential hydro-morphological impacts on the harbor area and adjacent navigational channel. The harbor experiences a steady accumulation of sediment. This results in a reduction of navigational depth and necessitates regular maintenance dredging constituting a cost aspect. A comprehensive field study was conducted, deploying a ridged inflatable boat (RIB) equipped with differential Global Positioning System, a winch for conductivity, temperature, and depth casting as well as sediment and water sampling and an acoustic Doppler current profiler for current profiling. Measurements reveal a tidally governed alternating flow pattern inducing a vortex current inside the harbor basin. Hydrodynamic sea floor grain sorting is detected through sediment sampling. A numerical model cascade is developed and calibrated against available tide gauge and sediment inventory data as well as multibeam survey data and acquired field measurements. The calibrated model cascade is used to simulate layout variants and compare resulting impacts to identify preferable jetty designs.

Sandy beaches generally are influenced by various coastal dynamic processes and undergo constant changes. The present study is an attempt to understand the hydromorphodynamic characteristics of a sandy pocket beach situated along the central west coast of India through field observation and numerical modeling. Multiple oceanographic instruments are deployed to capture the actual nearshore hydrodynamics, and sediment transport is measured using the streamer trap method suggested earlier during the premonsoon season. The observed vertical distribution of sediment fluxes showed a typical upward decrease from the seabed to the water surface. It is also noted that nearly 75% of the trap measurements showed that near-bed transport is higher than the depth-integrated values, confirming that the maximum sand remobilization is in the vicinity of the seabed rather than in suspension. The beach profiles of selected transects were measured during the pre- and postmonsoon seasons to understand the bed evolution. A one-dimensional numerical model, developed using XBeach and validated with field-observed values, demonstratively captured the effect of monsoon hydrodynamics on the beach profiles with fair accuracy. The various significant numerical parameters that govern the morphodynamics in the sandy beach are evaluated through a comprehensive analysis. In the end, the simulated beach profile that captures the effect of monsoon and storm are in good agreement with that obtained from field observations, with Brier Skill Scores (BSSs) of 0.69, 0.76, and 0.74 for Profiles 1, 2, and 3, respectively.

In this work, we carried out a case study of numerical simulations of low-frequency wave motions at the Marina di Carrara Harbor, where field observations have been conducted from 2005 to 2007. The fully nonlinear Boussinesq model, FUNWAVE-TVD, was applied to study the multiscale processes, including wind waves, infragravity waves, vortical eddies, and their potential effects on harbor operations. To reproduce the bound infragravity waves, the model was modified to take into account the second-order correction in wave generation based on weakly nonlinear second-order theory. Model–data comparisons show that the model correctly predicted the wave spectra in the low-frequency band and the overall long-wave energy inside the harbor. Additional numerical experiments, with different input wave characteristics, indicate that the directional spreading and incident wave direction play a role in predicting short waves inside the harbor, but have limited influence on the long-wave energy distribution, especially for the low-frequency band close to the resonant modes of the harbor. The second-order correction produces correctly the infragravity bands bounded with wave groups in the wave generation region. However, it does not modify the resonant modes and their magnitudes likely due to nearly “white” spectral structure, characterized by a nonzero constant power spectral density block or equivalently constant value/intensity of Fourier modes at different frequencies, in either bound or spurious infragravity waves.