Showing papers in "Ocean Engineering in 1991"

TL;DR: In this article, a regression equation is derived which predicts the probability of occurrence of double peaked spectra in open areas of the North Atlantic and North Sea for sea states higher than 3-4 m.

TL;DR: In this paper, the linearized hydrodynamic forces acting on multiple vertical axisymmetric bodies forced to oscillate either independently or as a unit in water of finite depth were investigated.

TL;DR: In this paper, the problems of radiation (both heave and sway) and diffraction of water waves by a submerged sphere in finite depth are formulated using the multiple method, which leads to an infinite system of linear equations which are easily solved numerically.

TL;DR: In this article, the authors measured the impact pressure of breaking waves on vertical, 5° forward, and 5, 10, 20, 30, and 45° backward sloping walls.

TL;DR: In this article, a survey of the generally used theories for predicting wave-induced motions and loads on ships as well as available comparisons with experimental results is presented, and a formulation is developed to quantify the influence of the transfer function uncertainty on the short-term response variance.

TL;DR: In this paper, the authors focus on the transient effects predicted by a one-equation turbulence closure model and present case studies in which waves are superimposed co-linearly on a current (forward problem) and are then removed from the converged wave-current flow (backward problem).

TL;DR: In this article, the diffraction of water waves by a uniform vertical circular cylinder in a channel is considered using the linear wave theory and an accurate and efficient method is developed for calculating the solution, and expressions for the transmission and reflection coefficients are obtained.

TL;DR: In this article, a multipole expansion of the velocity potential is described for two-and three-dimensional wave diffraction and radiation problems, where the wave terms and the local disturbance terms are represented by separated multipole potentials.

TL;DR: In this article, the authors demonstrate that an oscillating water column of given dimensions can be made to resonate at any chosen frequency of interest by controlling the phase of the load acting on it.

TL;DR: In this article, a time domain Modified Approximate method for calculating the dynamic tension of mooring chain is presented, and the calculated results of the slow drift oscillation of floating structure and dynamic tensions are compared with the experimental ones.

TL;DR: In this paper, the reflection of wave energy from natural beaches is studied and the issue of wave reflection is addressed via separation of input and output signals using coincident pressure and velocity measurements.

TL;DR: In this article, the rocking behavior and overturning stability of free-standing offshore equipment subjected to support excitations is investigated, and the response of non-slender (fully nonlinear) systems are more sensitive to perturbations in system and excitation parameters than their piecewise-linear counterparts.

TL;DR: In this article, the authors examined the characteristics of over-water gust factors and turbulence at three offshore locations, and evaluated several techniques for predicting overwater gusts, and found that gust factors were most sensitive to gust duration (t), elevation (z), and measuring interval (T).

TL;DR: In this paper, a single point taut moored buoy cable system is carried out in a 2 m-wide regular wave flume for different wave heights and wave periods, and the results are processed to plot the variation of acceleration and tension for various wave steepnesses and relative water depths which find applications in the study of the behaviour of mooring systems.

TL;DR: In this paper, the nonlinear oscillation of tension leg platform tethers induced by vortex shedding in a combined wave and current field is considered. And the effects of the drag and lift coefficients and the frequencies of the waves and parametric excitations have also been investigated.

TL;DR: In this article, a diffracted wave field around a rigid and surface-piercing single circular cylinder, multiple circular cylinders and cylinders of square and rectangular cross-sections, placed vertically in a wave flume, are obtained using the source distribution method.

TL;DR: In this article, an experimental investigation has been carried out on a wind-assisted ship propulsion device (WASP), consisting of a cylinder-flap wing with boundary layer suction, and measurements of the pressure distribution, lift and drag have been presented for various angular locations of the suction area and flap.

TL;DR: In this article, the Extended KdV (EKdV) equation for non-linear water waves in shallow water with cylindrical symmetry is established in the form of the extended kdV equation.

TL;DR: In this paper, the horizontal plane method was used to evaluate the first-order wave potentials on vertical cylinders of arbitrary geometry, and together with the near-field approach of Pinkster (1979, Ocean Engng6, 593-615) the second-order mean wave drift forces were calculated based on this numerical technique.

TL;DR: In this article, a combined wave refraction-diffraction numerical model was developed to predict wave conditions around an arbitrary island based on the mild-slope equation, solved using a finite difference scheme with a marching procedure.

TL;DR: In this article, the authors investigate the effective breadth of a stiffened plate, regarding both stiffness and strength, and compare various numerical solutions supplied by a finite-element program with solutions based on the beam theory.

TL;DR: In this article, the surface pressure vs concentration and area per molecule curves for monolayers of stearic acid, palmitic acid and oleic acid were determined on a clean artificial seawater surface using a modified Langmuir trough.

TL;DR: In this paper, an exact solution of the title problem was obtained in the case where one of the beam ends is elastically restrained against rotation and translation, and natural frequency coefficients were determined for a significant range of the parameters that come into play.

TL;DR: In this paper, a finite element geometric nonlinear analysis program has been developed for the analysis of single point sub-surface deep sea moorings, where the effect of diameter of the cable, drag coefficient, rope length, current velocity, current profile and buoyancy on the mooring configuration has been studied.

TL;DR: The structural stability of 42-ton dolos armor units, both unreinforced and pre-stressed and subject to wave-induced pulsating loads, are examined in this article.

TL;DR: In this paper, a general formulation encompassing a wide range of directional sea models is presented, and approximate expressions for the two frequency dependent parameters in a modified Longuet-Higgins cosine wave spreading model are presented.

TL;DR: In this paper, the amplitude of vibration of circular cylinders undergoing in-line vortex-induced excitation is demonstrated to be valid only for structures in uniform flows at sub-critical Reynolds numbers.

TL;DR: In this article, a linearization method is proposed for the vectorial Morrison equation which enables the force spectrum on an inclined cylinder to be calculated in a relatively simple manner from the wave spectrum in the presence of a current.

TL;DR: In this article, an approximate method for computing the wave forces on an array of vertical cylinders using the plane wave method has been proposed and shown to be a good approximation for regular arrays of 2, 3, and 5 cylinders by McIver and Evans.

TL;DR: In this article, an approximate method is presented for estimating the hydrodynamic forces on a pair of bottom-mounted, surface-piercing circular cylinders in waves of arbitrary uniform depth in the context of linearized potential flow.