Journal of Waterway, Port, Coastal, and Ocean Engineering

An effort has been made to improve quantitative understanding of beach morphology and stone structural damage progression and to develop a simple and robust model that is suited for engineering applications. The effort for the last 10 years has produced the cross-shore numerical model CSHORE, which is presently limited to the case of alongshore uniformity and uniform cohesionless sediment including sand, gravel, and stone. CSHORE consists of the following components: a combined wave and current model based on time-averaged continuity, cross-shore and longshore momentum, wave energy or action, and roller energy equations; a sediment transport model for suspended load and bed load; a permeable layer model to account for porous flow and energy dissipation; formulas for irregular wave run-up; a probabilistic model for an intermittently wet and dry zone on impermeable and permeable bottoms for the purpose of predicting wave overwash of a dune and armor layer damage progression, respectively; a drag force model for piles interacting with waves and sand dunes; and a dike erosion model by irregular wave action. The theories and formulas in CSHORE, which were published piece by piece, are assembled in this special issue to highlight the progress and shortcomings as well as to integrate coastal hydrodynamics, sediments, and structures for practical applications.

A review of the existing research on the interaction between a pipeline and an erodible bed exposed to waves and/or currents is presented. The review covers three topics: scour, liquefaction, and lateral stability of pipelines. The basic mechanism that leads to scour in two-dimensional (2D) and three-dimensional (3D) cases is first described, as deduced from small-scale laboratory experiments. The onset of scour from piping and the developing tunnel erosion are among the processes described. The lateral expansion of the scour hole along the pipe is described, also based primarily on small-scale laboratory experiments. The state of the art of the mathematical/numerical modeling of the scour processes is presented. The associated self-burial of the pipe is described and compared to field observations. In addition to scour, liquefaction may also constitute a risk for pipeline stability. The cause of liquefaction and the resulting consequence for pipeline stability in a natural environment are discussed. Finally, the lateral stability of pipelines placed on an erodible bed and exposed to waves is briefly described.

The mathematical modeling of the interaction of water waves with porous coastal structures has continuously been among the most relevant challenges in coastal engineering research and practice. Finding a tool to better predict essential processes, relevant to the functionality and stability of breakwaters and jetties, and how they are affected by permeability, has been hampered by computational limitations that are being overcome. Over the last 60 years, the Journal of Waterway, Port, Coast, and Ocean Engineering has witnessed gradual developments leading from linearized solutions based on wave theories and constant friction coefficients to very sophisticated Eulerian or Lagrangian solvers of the Navier-Stokes (NS) equations, including turbulence within porous media. Today, although not without difficulty, the first steps are being made toward addressing the simulation of a fully three-dimensional interaction of complete sea states with porous structures at prototype scale. In this paper, after posing the mathematical foundations of the problem, the solution techniques available in the literature are reviewed. Linear solutions based on potential theory; depth-integrated solutions, including Boussinesq approximations; and solutions based on the NS equations, in both the Eulerian and Lagrangian frameworks, are covered. Then, turbulence modeling on porous media is discussed. Conclusions and a discussion of future research directions close the paper. It is shown that, after so many years, some fundamental questions still remain unanswered, leaving challenges open for future research.

The development, testing, and implementation of a real-time tsunami forecast model, the method of splitting tsunami (MOST), is described. MOST is now used as an operational forecast model for the National Oceanic and Atmospheric Administration’s Tsunami Warning System, and as a tsunami hazard assessment tool in the United States and in many countries around the world. Every step in the development of MOST marked new scientific challenges, improvements of technological and computational capabilities, and new demands of the engineering and hazard mitigation communities for applied and benchmark modeling tools for tsunami hazard assessment.

In this paper, the development of a class of depth-integrated, phase-resolving models for surface wave propagation, known as Boussinesq-type models (BTMs), is reviewed. This review concentrates on the extension of the leading order formulation for weakly dispersive waves to include a range of physical effects and considers model applications at a range of scales ranging from surf zone processes to ocean basin–scale tsunami propagation. A brief overview of the connection of BTMs to nonhydrostatic models, in either depth-integrated or three-dimensional form, is included.

The interaction of nonlinear progressive waves and a uniform current in water of finite depth is investigated analytically by means of the homotopy analysis method (HAM). With HAM, the velocity potential of the flow and the surface elevation are expressed by the Fourier series, and the nonlinear free surface boundary conditions are satisfied by continuous mapping. Unlike a perturbation method, the present approach does not depend on any small parameters; thus, the solutions are suitable for steep waves and strong currents. To verify the HAM solutions, experiments are conducted in the wave–current flume of the Education Ministry Key Laboratory of Hydrodynamics at Shanghai Jiao Tong University (SJTU) in Shanghai, China. It is found that the HAM solutions are in good agreement with experimental measurements. Based on the series solutions of the validated analytical model, the influence of water depth, wave steepness, and current velocity on the physical properties of the coexisting wave–current field are studied in detail. The variation mechanisms of wave characteristics due to wave–current interaction are further discussed in a quantitative manner. The significant advantage of HAM in dealing with strong nonlinear wave–current interactions in the present study is clearly demonstrated in that the solution technique is independent of small parameters. A comparative study on wave characteristics further reveals the great potential of HAM to solve more complex wave–current interaction problems, leading to engineering applications in the offshore industry and the marine renewable energy sector.

A two-dimensional high-order Boussinesq-type model was derived to simulate wave propagation and relevant processes in the nearshore zone. Because of its enhanced nonlinear character, the model can describe more accurately the amplitude dispersion compared to its weakly nonlinear counterpart. Extension to the surf zone was accomplished using the eddy-viscosity concept for simulating breaking waves. Swash-zone dynamics were simulated by applying a modified narrow-slot technique. Bottom friction and subgrid turbulent mixing were also incorporated. The model can estimate the wave-induced current field, including the undertow effect. The numerical model relied on a generalized multistep predictor-corrector scheme, and the waves were generated using the source function method. Both the one-horizontal-dimensional (1DH) and two-horizontal-dimensional (2DH) versions were validated against a variety of experimental tests, including regular and irregular wave propagation and breaking on plane beaches and submerged shoals. Breaking and run-up of a solitary wave were also modeled. Furthermore, a wave overtopping test was also included. Oblique long-crested irregular wave incidence and a test including a rip channel were simulated to check the model's performance. The agreement, in general, is satisfactory, and most of the nearshore phenomena were accurately reproduced.

Estimation of the time-rate consolidation of dredged deposits is considerably complicated when vertical drains are installed to enhance the consolidation process of the soft-soil stratum, because the vertical drains are commonly installed before self-weight consolidation is complete. In this paper, two new methods are proposed to take into account both vertical and radial drainage conditions during the nonlinear finite-strain self-weight consolidation of dredged soil deposits (i.e., precise prediction of the self-weight consolidation behavior considering radial flow to the vertical drain). For one-dimensional nonlinear finite-strain consolidation in the vertical direction, the simplified Morris’s analytical solution and the primary consolidation, secondary compression, and desiccation of dredged fill (PSDDF) analysis are adopted. In addition, to consider the radial drainage, Barron’s vertical drain theory is used. The overall average degree of self-weight consolidation of the dredged soil is estimated using Carrillo’s formula, in which both vertical and radial drainage are considered. A series of large-scale self-weight consolidation experiments with consideration of a vertical drain were carried out to verify the simplified methods proposed in this paper. The use of the PSDDF results provides a more accurate estimation of overall average degree of self-weight consolidation considering the existence of a vertical drain than the use of the simplified Morris analytical solution.