Journal of Waterway, Port, Coastal, and Ocean Engineering

A recent development of a parabolic equation method for wave propagation in a non‐orthogonal coordinate system is reviewed. A transformation of the full governing equation prior to development of any approximation leads to a model whose results stand in closer agreement to laboratory data for a case of waves propagating into a breakwater harbor. The effect of amplitude dispersion on predicted wave height is studied and is also seen to be important for the case considered here. Reflection of obliquely incident waves by a vertical wall is also considered.

The short‐term cumulative probability distribution of peak wave forces, acting on vertical cylindrical elements, as obtained by the probabilistic method, may be accurately reproduced by a more direct approach, which expresses the cumulative probability of a peak force in terms of the probability integral of all waves producing peak forces below the stated value. The cumulative distribution offerees acting on a pair of cylindrical elements may also be obtained by this approach, and found to be in good agreement with results generated by the rigorous probabilistic method. In contrast with the probabilistic method, these results suggest that the present technique may be practically applied to a complete structure. Good agreement between theory and experiment is demonstrated.

Results from a series of numerical model runs predicting the shortterm physical fate of dredged material disposed in the open water of Puget Sound are presented along with a discussion of the numerical model applied. The first set of results is from a generic study covering a wide range of water depths and ambient currents. The range of conditions tested is intended to represent typical ambient conditions and material to be disposed in Puget Sound. The second set of results is from a study concerning the modeling of the fate of material to be dredged at the proposed U.S. Navy Home Port in Everett, Washington. Current plans call for disposal of the material at a site located in 81 m of water in Puget Sound. The approach under study is to dispose of the contaminated material from a bottomdumping barge to be capped by the following disposal of uncontaminated material from a surface pipeline with an attached splash plate to minimize the bottom impact of the capping material.

A model has been developed to describe wave climate in the areas of caustics where wave diffraction as well as refraction have important influences on wave propagation. Wave conditions are determined by solving the kinematic and dynamic conservation equations, which have been modified to include the effects of diffraction process. An approximate representation of nonlinear effect is also included by employing an empirical dispersion relation. The model is tested against laboratory measurements for the case of submerged circular islands on a slope, where both refraction and diffraction are equally significant, and shown to give good results.

The results of the writers' opposing wind laboratory experiments are developed for use in practical wave prediction problems. Relationships are presented for the decay of swell in opposing wind situations. An opposing wind source term for the radiative transfer equation is also developed which should enhance predictions in rapidly turning winds. The results indicate that steep high frequency wave components of the spectrum decay rapidly, leaving a narrow‐banded spectral representation. The results are in good agreement with the limited field data available.

The two‐dimensional problem of the interaction of periodic incident waves with a hinged inclined barrier is investigated theoretically and numerically in this study. A combination of the finite element method and an eigenfunction expansion procedure is used to obtain numerical solutions to this problem. The transmission characteristics and the effectiveness of a partially floating, inclined breakwater are studied. The effects of variations in the wave period, angle of inclination of the barrier, and the bottom gap are investigated. It is shown that results obtained by the numerical method compare reasonably well with the experimental data and other theoretical solutions.

Laboratory tests show that the selected muds, with sediment concentration from 150 to 500 g/l, can resist shear force even after they were severely disturbed. These tests were conducted to clarify why the Voigt element, a simple viscoelastic model, was selected to model the response of mud beds in the wave erosion tests. The viscoelastic constants (shear modulus and viscosity) of the selected sediments were also obtained. The shear modulus increases with the dry density and might reach to a plateau. Inasmuch as the different physical meaning of the viscosity for a viscous fluid and for a viscoelastic material, the viscosity decreases when increasing the dry density, but it decreases when the density is less than a specific value.

A semiempirical model for the prediction of shoreline advancement/recession of an initially plane beach is developed by using a conservation of sand argument and extending the equilibrium profile concept of Bruun and Dean in the surf zone to the depth of closure. When the initial each slope is greater than 1.2 times of the equilibrium slope, $m_e=h_c/W_c$, where $h_c$ is the depth of profile closure and $W_c$ is the offshore distance to $h_c$, the shoreline recession occurs, or vice versa. Using regression analyses on some available laboratory data, the magnitude of shoreline advancement is expressed in terms of initial plane beach slope, deepwater wave height and the Dean number. This expression is shown to give a good agreement with some field measurement data when the nearshore storm wave height that is exceeded only 12 hr/yr is used in place of the deepwater wave height.