Journal of Waterway, Port, Coastal, and Ocean Engineering

In terms of container handling, the port of Busan was ranked the third busiest port in the world in year 2002. As an advantage, the increased cargo volumes can provide higher profits, but, at the same time, can also cause port congestion. Busan has also suffered from severe port congestion recently. To accommodate the increased number of vessels calling at the port, the Korean government has already started the construction of new container terminals within the harbor. However, apart from simple studies, no specific evaluation of the port traffic has been performed until now. With this in mind, this paper aims to analyze the effects of ship traffic conditions in the year 2011 and to evaluate the potential for marine traffic congestion using the well established simulation language—the AWE-SIM simulation program. The findings reveal that the urgent tasks to prevent possible congestion are the elimination of anchorage $M$ , the reallocation of terminal functions in number two pier and enlarging of the superstructure of the container terminals.

In this paper, we study the scattering and trapping of wave energy by a submerged truncated paraboloidal shoal. The analytical approach of Liu et al. in 2004 for solving wave amplification around a circular island mounted on a shoal is extended in this study to investigate waves above a submerged shoal. In this approach, the mild-slope equation is first transformed into an explicit equation by using Hunt’s 1979 Padé approximation to the wave dispersion equation. It is then solved analytically in terms of combined Fourier series and Taylor series. For incident waves varying from short to long waves, wave amplifications in the vicinity of the shoal are calculated using the newly derived analytical model and they agree excellently with the finite difference solutions of Lin in 2004. It is found that, for the particular shoal studied in this paper, there exists an energy focal point where the wave amplitude is the maximum. This point is the result of combined wave refraction, diffraction, and reflection. The point is always located along the $x$ -axis and it is behind the shoal center for very short waves. As the increase of wave period, it moves upstream and it can come in front of the shoal center for very long waves when wave reflection is significant. For a particular incident wave, wave amplification increases and the focal point moves toward the shoal center with the reduction of the water depth above the shoal center. The maximum wave amplitude increases exponentially as the decrease of local water depth. It is also found that there exists the so-called “calm” areas for shallowly submerged shoal, which are located behind the focal point and the local amplitude can be as small as nearly zero.

A numerical model based on time-averaged continuity, momentum, and energy equations is developed to predict the mean and standard deviation of the free surface elevation and horizontal fluid velocities above and inside a porous submerged breakwater. The energy dissipation rate due to irregular breaking waves is estimated using an existing formula that is modified for intense wave breaking on the steep seaward slope of the breakwater. This computationally efficient numerical model is an extension of the existing time-averaged model which is widely used to predict irregular breaking wave transformation on impermeable beaches. The developed model is shown to predict the cross-shore variations of the mean and standard deviation of the free surface elevation measured in a laboratory experiment where a submerged porous breakwater was placed on a gentle impermeable slope. The agreement for the measured horizontal velocity is marginal partly because this one-dimensional model does not predict the vertical velocity variation. This semiempirical model calibrated using the present experiment will need to be compared with additional experiments.

Self-burial of finite-length cylinders under pure oscillatory flow was studied with a large oscillating water-sediment tunnel (LOWST). Cylindrical models were placed on a $60\mathrm{cm}$ deep sandy bed and measurements of cylinder burial were made with the aid of video cameras. Thirty experiments were completed for a wide range of flow conditions to investigate burial due to scour of cylinders having length-to-diameter ratios between two and four. Experimental results showed a strong correlation between the Shields parameter and the equilibrium burial depth. On the other hand, the correlation between the equilibrium burial depth and the Keulegan-Carpenter number, commonly used to determine equilibrium scour depth of pipelines, was found to be less strong for the current case of short cylinders. Length-to-diameter ratio, density, and initial burial of the models were not found to influence the equilibrium burial depth. A time interval, necessary for burial initiation, was defined. The time scale for the burial of a cylindrical object was also identified and characterized by a semiempirical equation. Based on the observations, a new equation to estimate the burial of finite-length cylinders is advanced and a procedure to estimate the burial process is proposed.

A ship maneuvering simulator is a valuable tool for evaluating conditions that may be considered as critical from a nautical point of view. The full mission bridge simulation study described in this paper has been performed to assess the maneuvering behavior of large container vessels in navigation areas with bottoms covered with fluid mud deposits. The input for the simulator consisted of a mathematical model based on results of extensive captive model test series. The presented qualitative and quantitative analysis of the simulation runs provides a solid basis for an advice for a new definition of the nautical bottom in the harbor of Zeebrugge, which fully takes into account all significant effects on ship controllability.

Nonlinear wave-current interactions with fixed or freely floating bodies are investigated by a two-dimensional (2D) fully-nonlinear numerical wave tank (NWT). The NWT is developed based on the potential theory and boundary element method (BEM) with constant panels. Mixed Eulerian-Lagrangian (MEL) time marching scheme (material-node approach) is used with fourth-order Runge-Kutta fully updated time integration, regriding, and smoothing techniques, and acceleration-potential formulation and direct mode-decomposition method. Specially devised ${\varphi }_n-\eta$ type artificial damping zones (i.e., numerical beach) are implemented to prevent wave reflection from the end wall and wave maker. Using the developed NWT, nonlinear wave-current interactions (1) without bodies; (2) with a stationary body; and (3) with a floating body for various wave and current conditions have been investigated and some of the NWT simulations are compared with the results of Boussinesq’s equation and perturbation theory. It is seen that the NWT results reproduce the general trend of linear or perturbation theory in free-surface profiles, runup, forces, and motions but their magnitudes can be appreciably different from the perturbation-based solutions as wave steepness and current velocity grow.

We utilize beach profile data from 37 profile locations on the Atlantic coast of Delaware that were surveyed an average of 12 times between 1964 and 1993 to assess the validity of several equilibrium beach profile (EBP) formulations. Under consideration are (1) a power law formulation; (2) a formulation including the effects of downslope transport; and (3) a modified form of the latter model suggested herein. We perform a least-square fit of these models to the individual observed profiles, the mean profiles at the 37 locations, as well as regionally averaged profiles over eight geographically distinct regions. The analysis results in best-fit values for the model coefficients. The results indicate that the first model is robust and predicts observed mean and regionally averaged profiles with an estimated normalized error of 26 and 15%, respectively. However, the predicted beach slopes near the shoreline are infinite and, hence, unphysical. The second model includes the effects of downslope transport and remedies this shortcoming. Predictions are drastically improved (15 and 6% relative errors for mean and regionally averaged profiles, respectively), but the coefficient values required for these predictions are outside of the physically justifiable range for beaches with an average slope that is of comparable magnitude to the foreshore slope. When physically realizable coefficient values are used the predictive skill of this model is low (with relative errors up to 50% for the regionally averaged profiles). We find that the problem arises because of the dominance of the gravity-related term over much of the profile and suggest a heuristic remedy that restricts the effect of the gravity term to a region close to the shoreline. This modified model has a high skill (15 and 6% relative errors for mean and regionally averaged profiles, respectively) while still retaining robust and reasonable values for the model coefficients.

This technical note shows some results of a small-scale field experiment on Boccotti’s submerged caisson breakwater, which absorbs wave energy and is able to defend a coast with a very small environmental impact. The experiment on the 1:10 scale model of a caisson of this breakwater was carried out on a $2.6\text{-}\mathrm{m}$ -deep seabed. All the records of the experiment confirm that it is possible to obtain a strong natural resonance between the random process of wave pressure at the outer opening of the caisson and the random process of oscillations inside the caisson. Finally, a test of the computational algorithm is given by means of the output of the field experiment, and a procedure for tuning the plant is also given.