Showing papers in "Ocean Engineering in 1987"

TL;DR: An efficient algorithm is presented which simulates the three-dimensional motion of a towed cable using an implicit, second-order finite difference approximation of the equations of motion.

TL;DR: In this article, the adequacy of a simple theoretical model for the joint distribution under stationary conditions is investigated, using measurements achieved during storms in Northern North Sea, in a slightly modified form the model is found to be of a reasonable accuracy as far as the highest waves are of interest.

TL;DR: In this article, a statistical analysis of unidirectional non-linear random waves is presented which is based on second-order random wave theory, and the analysis technique is similar to a method which is available for the statistical analysis for the two-term Volterra series.

TL;DR: In this article, the free surface (z = 0 ) condition was simplified and the effects caused by the variation in the added mass with cylinder submergence in both modes were investigated.

TL;DR: In this paper, three theoretical joint distributions of wave height and period are compared with data, and the effect of high frequency cut-off on the distribution of wave length and period is considered.

TL;DR: The hydrodynamic force model for pipelines presented in this paper includes flow history effects (wake effects) and time dependence in the force coefficients, which are necessary to obtain satisfactory agreement between model predictions and full scale field measurements of pipeline forces.

TL;DR: In this paper, the maximum power and efficiency of an irreversible OTEC heat engine were investigated and it was shown that there is a bound on the efficiency of the real OTEC Heat Engine at a given maximum power condition.

TL;DR: In this article, the authors analyzed continuous wave data from Scilly Isles during two storms in December 1981, and found significant correlations between the scale parameters (α and φ m ) are found during both storms.

TL;DR: In this paper, an approximate method is presented to estimate the hydrodynamic loading and associated structural response of each of a pair of free-standing, bottom-nounted, flexible circular cylinders subjected to a regular train of linear surface waves.

TL;DR: In this article, a two-dimensional avalanche model is used to estimate the speed and growth characteristics of potential turbidity currents downslope for various postulated marine conditions of initial flow density, height, volume, and length at slopes from 5 to 60°.

TL;DR: In this paper, an extrapolated version of a time-dependent nonreflecting boundary condition is developed for use at artificial boundaries to truncate infinite/semi-infinite domains for transient water wave problems.

TL;DR: In this paper, the Morison equation and the least square method were used to evaluate the hydrodynamic coefficients of a submarine pipeline in terms of maximum transverse force and transverse root mean square (r.m.) coefficients.

TL;DR: In this paper, Monte Carlo simulation of wave spectra was carried out to provide an assessment of JONSWAP spectral model and parameters and the simulation method is found to be satisfactory because (a) it excludes the spectral variability due to geophysical factors from the sampling errors in the spectral estimates and the statistical uncertainty in determining the model parameters; and (b) the simulated spectra can represent ideal spectral estimates where the sampled errors have been minimized by increasing the degrees of freedom of the spectra.

TL;DR: In this article, a method for stochastic fatigue analysis of offshore platforms is presented, which accounts for the nonlinearity in the drag loading term, and for the systematic deviation from a Gaussian process for a platform response.

TL;DR: In this paper, an analytical model was developed for the dynamic analysis of an articulated loading platform in an operation condition, while remaining in a head seas position, and the hydrodynamic load on the tanker was calculated using linear diffraction theory based on the 2D Helmholtz equation.

TL;DR: In this article, the theoretical analysis of the response characteristics of a caisson plate, having different aspect ratios, under the wave impact loading is investigated, and numerical results for the dynamic values of moments and transverse displacements are obtained by the method of finite elements.

TL;DR: In this article, the fundamental frequency of vibration of plates elastically restrained against rotation along the edges and with centrally located circular or square holes is determined by means of the optimized Rayleigh's method.

TL;DR: In this article, the mean aerodynamic force and moment coefficients of a typical tension leg platform for various approach wind directions were measured on a scale model exposed to simulated flow conditions in a boundary layer wind tunnel.

TL;DR: In this article, an objective assessment of three published wave spectrum formulas for the shallow sea is presented, and the results show that the models each have various degrees of effectiveness and applicability.

TL;DR: In this paper, a mathematical model for simulating cable dynamics was introduced in order to determine typical behaviour patterns of half-turn manoeuvres for the various immersions envisaged (from 2000 to 6000 m).

TL;DR: In this article, a practical method has been formulated to predict the second order wave loads on large offshore structures, including cylinders and square caissons, and the theoretical predictions have been compared with the experimental measurements and the comparison shows good agreement.

TL;DR: In this article, Bernouilli's classical theory is used to solve the simply supported beam, simply supported - clamped and clamped-clamped situations for the case of a concentrated load which varies sinusoidally with time.

TL;DR: In this paper, a new analysis of nonlinear rolling carried out by the multiscale perturbation method is presented, where the behavior of a ship in a regular beam sea is considered and approximate analytical solutions in three nonlinear resonance regions are obtained.

TL;DR: In this article, an experimental study of the effects of wave grouping on the slowly varying drift oscillations of a floating moored rectangular barge has been presented, which incorporates existing techniques to simulate wave groups with those that predict the slow varying drift response of a moored model.

TL;DR: In this paper, an approximate method is presented to estimate the hydrodynamic loading and structural response of an idealized offshore platform subjected to a regular train of linear surface waves, where the response of each column is assumed to be one-dimensional and to be governed by linear beam theory.

TL;DR: In this paper, the acceleration of an oscillating cylinder in water is analyzed by a Kalman extended filter and an assymetric drag coefficient variation over the oscillation period is estimated.

TL;DR: In this paper, the wave diffraction problem on axisymmetric structures is solved by treating the fluid field as two separate domains, i.e., the velocity potential in the inner domain is represented by a 1 r type Green's function whilst that of the outer domain was represented by an eigenfunction expansion.

TL;DR: In this article, an approximate analytical analysis is demonstrated to obtain the approximate wave forces on rectangular caissons fixed vertically on the sea-bed, and a data plot has been depicted to show the effect of linear forces for the case of rectangular Caissons and that for square CAissons.

TL;DR: In this article, a 3D model methodology for predicting the upper ocean currents under the combined influence of Gulf Stream and hurricane is described, and a potentially worst case condition is obtained for the so-called resonant hurricane.

TL;DR: In this article, an EOF analysis is used in conjunction with Markov chains to generate simultaneous current time series at several depths with a random walk model, which has been tested on data from Haltenbanken.