Journal of Waterway, Port, Coastal, and Ocean Engineering

A numerical model is presented that predicts the transformation of monochromatic waves over complex bathymetry and includes both refractive and diffractive effects. Finite difference approximations are used to solve the governing equations, and the solution is obtained for a finite number of rectilinear grid cells that comprise the domain of interest. Model results are compared with data from two experimental tests, and the capability and utility of the model for real coastal applications are illustrated by application to an ocean inlet system.

Time and frequency domain models that relate a vector time series at any location to a measured series at another location are presented and evaluated by application to the prediction of coastal currents. The time domain model belongs to the general class of cross‐autoregressive integrated (CARI) models based on classical time series analysis methods. The frequency domain model is a spectral component (SC) model, which relates the Fourier spectrum at different stations. The errors resulting from the use of both model types to predict measured currents off San Francisco, California, were computed. It was found that of the CARI models, a six parameter model was best, although a simpler three parameter model was almost as good. The main drawback to the CARI model was the nonstationarity of the formulation, requiring several years of data to develop a stationary model for a particular season. The SC model was more stationary and had smaller errors than the best CARI model. It is concluded that frequency domain models are the best method of predicting two‐dimensional vector time series from other series.

Submerged multiport diffusers are often used to discharge waste heat resulting from once‐through cooling at coastal power plants. A particularly effective design, known as a staged diffuser, involves nozzles oriented offshore, parallel with the diffuser pipe. Potential flow analyses are used to describe the far field entrainment region for a staged diffuser discharging to quiescent receiving water of either constant depth or linear sloping bottom. Boundary conditions, in the form of a distributed sink, are supplied by a simplified near field model. Whereas near field theory shows that dilution can be increased by increasing discharge velocity, extending diffuser length or siting in deeper water, the latter options are shown to be preferable from the standpoint of minimizing induced velocities and the magnitude of nearshore entrainment.

Using a conservation of sand approach, the effects of a rising sea surface are quantified and separated from other causes of shore retreat. Sitespecific data important in predicting shoreline changes are: (1) Initial shoreface and backbeach profile; (2) subsequent backbeach profile; (3) relative sea level rise; (4) grain size distribution of sediment landward of the shoreface; and (5) net quantity of sand‐sized material that enters or leaves a specified coastal reach. A key element of the approach, Bruun's assumption of a shoreface is dynamic equilibrium with the sea surface, was evaluated and found to be reasonably accurate. Field application of the method shows that sea level rise accounts for about 53% of the total shore retreat of 5.5 m/yr measured at Smith Island, Virginia, and for about 88% of the measured, 1.7‐m/yr retreat of the barrier island south of Oregon Inlet, North Carolina. Net sand losses account for the remainder. Because shoreface adjustments are required to maintain an equilibrium profile, sand replenishment is probably the most realistic method to stabilize a shore against the effects of relative sea level rise. Conversely, a negative sediment budget may also be mitigated by structures which hinder the movement of sand away from a problem beach and enhance its deposition there.

Internal hydrodynamic forces on submerged tanks due to arbitrary seismic excitations are evaluated. The transfer function of the lateral force is evaluated using Laplace transform. A mechanical analog duplicating such hydrodynamic forces is developed and checked for several limiting cases. The study shows that sloshing at liquids' interface can be neglected in the evaluation of such forces.

Navigation locks can strongly influence the water management of an area (both quantity and quality) especially if they belong to a retaining dike separating saltwater from fresh water. Then these locks consume fresh water for the locking process. An extra quantity is also needed for the reduction of salt intrusion. In the past 30 years, various locks with devices to reduce the salt intrusion have been developed especially in The Netherlands. The state of the art of this development is presented. The performance of the various devices will also be described. The major characteristic of the development is a decreasing consumption of fresh water to reduce the salt intrusion combined with an increasing complexity of the devices.

The hydrodynamic forces on a horizontal cylinder, either in waves or in waves and towing, are determined experimentally for a Reynolds number up to $5\times {10}^5\text{.}$ The differences of the wave force coefficients between a horizontal cylinder in waves and in planar oscillatory flow are shown. The effects of a current on the force coefficients are examined. It is shown that hydrodynamic forces on a cylinder towed in a wave field can be simulated if the linear superposition principle is assumed.

The distribution of suspended sediment in the combined wave‐current motion is theoretically predicted in the case of a plane bed. This will be the case if the wave‐induced motion close to the bed is sufficiently strong. The theory is able to predict the average value of the concentration as well as the instantaneous values at a given distance from the bed. The theory is compared with laboratory and field measurements.

A model developed to optimize the design and operation of containerports is described and demonstrated. The model minimizes total port costs, including the costs of dock labor, facilities and equipment, ships, containers, and cargo. It accounts for queueing delays to ships, mutual interference among cranes, minimum work shifts, and storage yard requirements. Model results are mainly used to determine the optimal combination of berths and cranes under various circumstances and to show that total costs per ship or unit of cargo served can be reduced by increasing the number of cranes per berth and berth utilization above present levels.

Some of the recent test results on steady and oscillatory flow past inclined circular cylinders are discussed. More specifically, the experimental error in results presented by Sarpkaya, et al, for oscillatory flow is described and the formula for the necessary correction factor is given. Contrary to earlier conclusions based on such erroneous results, the corrected results support the cross-flow principle very well, in general, in the case of the inertia coeeficient and at the larger Reynolds number and Keulegan-Carpenter number in the case of the drag coefficient.

A method is given for representing the action of a seawall in the 1-line numerical model of shoreline evolution. The method involves restriction of the shoreline position and adjustment of the longshore sand transport rate so as to conserve sand volume and preserve direction of transport. Sample calculations are presented, and the results are in accord with experience.