Journal of Waterway, Port, Coastal, and Ocean Engineering

The impact of a single wave generated by a dam break with a tall structure is modeled with a three-dimensional version of the smoothed particle hydrodynamics method. The method is used to analyze the propagation of a long wave and the force it exerts on a tall structure located in a region with vertical boundaries. Velocities and forces obtained from a numerical model are shown to be in good agreement with laboratory measurements. The effect of having a dry bed in front of the dam prior to the dam break versus a wet bed in the experiment is discussed.

In this paper a description of the major groups of marine organisms causing significant wood pile damage is presented. These organisms are divided into two groups: (1) fungi and (2) marine borers. The basic physical and biological characteristics of these organisms are presented, as well as the type of damage that they cause in marine wood piles. The objective of the study presented in this paper is to characterize deterioration of wood piles due to marine organisms and to assess damage in the wood pile zones of a typical waterfront installation. Marine borer activity in Maine coastal waters is assessed through a survey directed to harbor masters; the results of the survey are correlated with historic data. In order to illustrate the type and extent of wood pile deterioration, two case studies in Maine harbors are presented.

This paper presents a new method for engineering design that allows controlling safety factors and failure probabilities with respect to different modes of failure. Since failure probabilities are very sensitive to tail assumptions, and safety factors can be insufficient, a double check for the safety of the engineering structure is done. The dual method uses an iterative process that consists of repeating a sequence of three steps: (1) an optimal (in the sense of optimizing an objective function) classical design, based on given safety factors, is done, (2) failure probabilities or bounds of all failure modes are calculated, and (3) safety factor bounds are adjusted. The three steps are repeated until convergence, i.e., until the safety factor lower bounds and the mode failure probability upper bounds are satisfied. In addition, a sensitivity analysis of the cost and reliability indices to the data parameters is done. The proposed method is illustrated by its application to the design of a rubble-mound breakwater.

Laboratory experiments were conducted in a 2D wave tank, where a Plexiglas plate was installed in order to understand the runup and breaking of internal waves over a sloping boundary. During the experiments, a fluid consisting of fresh water and salt water was prepared to imitate the density-stratified ocean. An image processing technique was used to reveal the profile of internal waves and the mixture of the upper-layer and lower-layer water. The measured wave profiles were compared with the calculated results by the method of characteristics. The major feature of the runup processes was well reproduced by the theoretical solution, except for the upper slope region. Calculation using the $k-\epsilon$ model was carried out, and the predicted density variation due to mixing was compared with a set of luminance data analyzed by the image processing technique.

This study is concerned with two hydrodynamic parameters that are essential for the construction of submerged dikes in rivers with sand-filled geosynthetic bags. First, laboratory study and field observation are conducted to investigate the horizontal settling distance of sandbags in open channel flows. Sandbag models used for laboratory tests are prepared according to similarity requirements. An analytical formula for evaluating the settling distance is then derived based on the experimental data. The predictions are then compared to the field measurements. The observed settling distance varies significantly and its probability density distribution is positively skewed. This study also presents a formula for computing the critical flow velocity at incipient sandbag motion for two extreme conditions.

This paper deals with the development of a spectral feedback control technique capable of generating precise Gaussian wave packets and incipient breaking waves at predetermined locations in a laboratory wave flume. The design of the system includes the development of algorithms to generate the mathematical equations that define the wave packets and the spectral control algorithm for continuously correcting the system frequency response characteristics. Descriptions of the mathematical model of the Gaussian wave packets and their corresponding frequency spectra are given, along with the procedure used for spectral feedback compensation, especially with regard to handling the phase. The results of comparing wave packets generated by open and closed loop control systems are discussed. Experimental results are also used to demonstrate the adequacy of the spectral feedback technique to accurately generate particular Gaussian wave packets with particular emphasis on the important role played by the phase in reconstruction of transient signals. In addition, a method for generating breaking waves is explained and the results of experiments presented. Using the technique developed, resultant breaking wave packets of similar shape can be repeatedly produced at a predetermined location along the flume.