This article presents a collaborative research program that the Massachusetts Institute of Technology (MIT) and National Renewable Energy Laboratory (NREL) have undertaken to develop innovative cost-effective floating mooring systems for offshore wind turbines in water depths 10-200 m.Methods coupled structural, hydrodynamic, aerodynamic analysis turbine are presented frequency domain.This was conducted by coupling aerodynamics structural dynamics code FAST [4] developed at NREL with wave...

Aeroelastic simulation tools are routinely used to design and analyze onshore wind turbines, in order obtain cost effective machines that achieve favorable performance while maintaining structural integrity. These employ sophisticated models of wind-inflow; aerodynamic, gravitational, inertial loading the rotor, nacelle, tower; elastic effects within between components; mechanical actuation electrical responses generator control protection systems. For offshore additional hydrodynamic...

Wind is the fastest growing renewable energy source, increasing at an annual rate of 25% with a worldwide installed capacity 74 GW in 2007. The vast majority wind power generated from onshore farms. Their growth however limited by lack inexpensive land near major population centers and visual pollution caused large turbines. offshore farms next frontier. Large sea areas stronger steadier winds are available for farm development 5MW turbine towers located 20 miles coastline invisible. Current...

The properties of steady and unsteady ship waves propagating on a free surface discretized with panels are studied. wave propagation is characterized by an explicit discrete dispersion relation which allows the systematic analysis distortion pattern due to discretization derivation stability criterion be met numerical algorithm. conclusions study applied panel method used for computation time-harmonic free-surface flows past elementary singularities hull.

The paper presents a method that removes the effects of all irregular frequencies in boundary-integral equations governing interaction regular waves with floating bodies general geometry. A modified integral equation is obtained by linear superposition classical Green and its normal derivative respect to field point. selection purely imaginary constant proportionality ensures removal continuous problem appropriate magnitude eliminates their undesirable numerical implementation. Computations...

The large-amplitude rectilinear ‘slow-drift’ oscillation of a floating body constrained by weak restoring force in random waves is considered. free-surface flow approximated perturbation series expansion for small slow-drift velocity and wave steepness. A model equation motion derived, the time-dependent excitation damping coefficient are defined complete problems governing their magnitude formulated. problem wave-drift monochromatic studied an explicit solution obtained vertical circular...

The nonlinear long waves generated by a disturbance moving at subcritical, critical and supercritical speed in unbounded shallow water are investigated. problem is formulated new modified generalized Boussinesq equation solved numerically an implicit finite-difference algorithm. Three-dimensional upstream solitary with significant amplitude periodicity pressure distribution or slender strut advancing on the free surface. crestlines of these solitons almost perfect parabolas decreasing...

Abstract A new formulation is presented of the nonlinear loads exerted on floating bodies by steep irregular surface waves. The forces and moments are expressed in terms time derivative fluid impulse which circumvents time-consuming computation temporal spatial derivatives Bernoulli’s equation. hydrostatic force a body shown to point vertically upwards Froude–Krylov moment derived as an that involves simple integral ambient velocity potential over time-dependent wetted surface. radiation...

The steady wave patterns, Kelvin-wake spectra and resistance of several realistic ship hulls are computed by a Rankine panel method. Wall-sided as well transom-stern ships studied over broad range Froude numbers the importance enforcing Kutta-type condition smooth flow detachment at transom stern is demonstrated. lack numerical damping in solution scheme permits reliable prediction Kelvin wake far from allows its use evaluation free spectrum. evaluated pressure integration momentum...

The seakeeping performance is studied of a foil-assisted high-speed monohull vessel using state-of-the-art three-dimensional Rankine panel method. equipped with bow hydrofoil acting as passive heave and pitch motion-control device in waves. formulation the ships lifting appendages developed, mechanisms responsible for reduction motions high- speed vessels hydrofoils are studied. sensitivity on longitudinal position It found that most efficient location at ship leading to 50% root mean square...

A numerical technique is presented for the solution of deep water linear and time-harmonic wave-body-interaction problems in two dimensions. mathematical boundary circular shape surrounding body introduced fluid domain, thus defining flow regions. multipole expansion valid outer region then matched to an integral representation inner which obtained by applying Green's theorem using fundamental logarithmic singularity as Green function. The method applies both surface-piercing submerged...

Wind is a rapidly growing renewable energy source, increasing at an annual rate of 30%, with the vast majority wind power generated from onshore farms. The growth these facilities, however, limited by lack inexpensive land near major population centers and visual impact caused large turbines.Wind floating offshore farms next frontier. Vast sea areas stronger steadier winds are available for farm development 5 MW turbine towers located 20 miles coastline invisible. Current turbines supported...

A new stochastic representation of a seastate is developed based on the Karhunen–Loeve spectral decomposition signals and use Slepian prolate spheroidal wave functions with tunable bandwidth parameter. The allows description ocean waves in terms few independent sources uncertainty when traditional Fourier series requires an order magnitude more components. leads to parsimonious models ambient kinematics nonlinear loads responses ships offshore platforms. discussed for derivation critical...

A linear theory is presented for the scattering of small-amplitude monochromatic and unidirectional free-surface waves by a ship fixed at its mean advancing position. In an inner region close to hull geometrical slenderness used justify quasi-two-dimensional approximation flow. The method matched asymptotic expansions then introduced enforce compatibility solution with three-dimensional in far field. shown be uniformly valid all wavelengths practical interest angles wave incidence....

Artificial Intelligence (AI) Support Vector Machine (SVM) learning algorithms have enjoyed rapid growth in recent years with applications a wide range of disciplines often impressive results. The present paper introduces this machine technology to the field marine hydrodynamics for study complex potential and viscous flow problems. Examples considered include forecasting seastate elevations vessel responses using their past time records as “explanatory variables” or “features” development...

A nonlinear numerical method has been developed to compute motion responses for a ship traveling in steep ambient waves. The is based on an approximate theory and extension well-established linear time-domain method. solution found be greatly improved over the classical quasi-nonlinear solutions, comparison experimental measurements conventional commercial ships. Through this study, it also demonstrated that free surface hydrodynamic nonlinearities are at least as important as, if not more...