Download or read book Data driven Hydrodynamic Models for Heaving Wave Energy Converters written by Virag Mishra and published by . This book was released on 2020 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Empirical models based on linear and nonlinear potential theory that determine the forces on Wave Energy Converters (WECs) are essential as they can be used for structural, mechanical and control system design as well as performance prediction. In contrast to empirical modelling, Computational Fluid Dynamics (CFD) solves the mass and momentum balance equations for fluid domains. CFD and linear potential theory models represent two extreme in terms of capturing the full range of hydrodynamic effects. These are classified as white box models and the structure of these models is completely derived from first principles understanding of the system. In contrast black box models like a Artificial Neural Networks and Auto-Regressive with, Exogenous Input (ARX), map input and output behaviour of a system without any specific physics based structure. Grey box models do not strictly follow a first principles approach but are based on some observations of relationships between the hydrodynamic effects (e.g. buoyancy force) and system state (e.g. free surface height). The objective of this thesis is to propose a data driven grey box modelling approach, which is computationally efficient compared to high fidelity white box mod- els and still sufficiently accurate for the purpose of determining hydrodynamic forces on heaving WECs. In this thesis, a unique data driven approach that combines features from existing works in modelling of WEC and application of nonlinear hysteretic systems is developed. To that end a CFD based Numerical Wave Tank that could provide the data needed to populate the new modelling framework is used. A hull which hydrodynamically represents a Self Reacting Point Absorbers (SRPAs) with heave plate is subjected to pan-chromatic wave fields and is forced to oscillate concomitantly. The results provide evidence that a SRPA with heave plate exhibits nonlinear relationships with motion parameters including relative position, velocity and acceleration. These parameters show causal relationships with the hydrodynamic force. A simulation methodology to establish confidence in the components of a model framework is developed and the hydrodynamic forces on SRPAs with heave plate and bulbous tank have been analyzed and compared. Two sets of numerical simulation were conducted. Firstly, the WECs were restricted to all degrees of freedom and subjected to monochromatic waves and later the WECs were oscillated at various frequency in a quiescent numerical tank. These results were validated against existing experimental data. Earlier attempts by other authors to develop a data-driven model were limited to simple hulls and did not include rate dependent nonlinearities that develop for heave plates. These studies laid the foundation to current work. The model framework developed in this thesis accounts for the nonlinear relationship between force and parameters like velocity and acceleration along with hysteretic relationship between force and velocity. This modelling framework has a nonlinear static, a hysteresis (Bouc-Wen model) and a dynamic (ARX model) block. In this work the Bouc-Wen model is employed to model the hysteresis effect. Five different models developed from this modelling framework are analyzed; two are state dependent models, while the other three required training to identify dynamic order of model equations. These latter models (Hammerstein, rate dependent Hammerstein and rate dependent KGP models) have been trained and validated for various cases of fixed and oscillating HP cylinder. The results demonstrate significant improvement (max 39%) in prediction accuracy of hydrodynamic forces on a WEC with heave plate, for the model in which a rate dependent hysteresis block is coupled with Hammerstein or KGP models.

Download or read book Numerical Modelling of Wave Energy Converters written by Matt Folley and published by Academic Press. This book was released on 2016-06-14 with total page 308 pages. Available in PDF, EPUB and Kindle. Book excerpt: Numerical Modelling of Wave Energy Converters: State-of-the Art Techniques for Single WEC and Converter Arrays presents all the information and techniques required for the numerical modelling of a wave energy converter together with a comparative review of the different available techniques. The authors provide clear details on the subject and guidance on its use for WEC design, covering topics such as boundary element methods, frequency domain models, spectral domain models, time domain models, non linear potential flow models, CFD models, semi analytical models, phase resolving wave propagation models, phase averaging wave propagation models, parametric design and control optimization, mean annual energy yield, hydrodynamic loads assessment, and environmental impact assessment. Each chapter starts by defining the fundamental principles underlying the numerical modelling technique and finishes with a discussion of the technique’s limitations and a summary of the main points in the chapter. The contents of the chapters are not limited to a description of the mathematics, but also include details and discussion of the current available tools, examples available in the literature, and verification, validation, and computational requirements. In this way, the key points of each modelling technique can be identified without having to get deeply involved in the mathematical representation that is at the core of each chapter. The book is separated into four parts. The first two parts deal with modelling single wave energy converters; the third part considers the modelling of arrays; and the final part looks at the application of the different modelling techniques to the four most common uses of numerical models. It is ideal for graduate engineers and scientists interested in numerical modelling of wave energy converters, and decision-makers who must review different modelling techniques and assess their suitability and output. Consolidates in one volume information and techniques for the numerical modelling of wave energy converters and converter arrays, which has, up until now, been spread around multiple academic journals and conference proceedings making it difficult to access Presents a comparative review of the different numerical modelling techniques applied to wave energy converters, discussing their limitations, current available tools, examples, and verification, validation, and computational requirements Includes practical examples and simulations available for download at the book’s companion website Identifies key points of each modelling technique without getting deeply involved in the mathematical representation

Download or read book Linear and Nonlinear Parametric Hydrodynamic Models for Wave Energy Converters Identified from Recorded Data written by Simone Giorgi and published by . This book was released on 2017 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Hydrodynamic Control of Wave Energy Devices written by Umesh A. Korde and published by Cambridge University Press. This book was released on 2016-09-26 with total page 385 pages. Available in PDF, EPUB and Kindle. Book excerpt: With this self-contained and comprehensive text, students and researchers will gain a detailed understanding of the fundamental aspects of the hydrodynamic control of wave energy converters. Such control is necessary to maximise energy capture for a given device configuration and plays a major role in efforts to make wave energy economic. Covering a wide range of disciplines, the reader is taken from the mathematical and technical fundamentals, through the main pillars of wave energy hydrodynamic control, right through to state-of-the-art algorithms for hydrodynamic control. The various operating principles of wave energy converters are exposed and the unique aspects of the hydrodynamic control problem highlighted, with a variety of potential solutions discussed. Supporting material on wave forecasting and the interaction of the hydrodynamic control problem with other aspects of wave energy device optimisation, such as device geometry optimisation and optimal device array layout, is also provided.

Download or read book Handbook of Ocean Wave Energy written by Arthur Pecher and published by Springer. This book was released on 2016-12-07 with total page 305 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book is open access under a CC BY-NC 2.5 license. This book offers a concise, practice-oriented reference-guide to the field of ocean wave energy. The ten chapters highlight the key rules of thumb, address all the main technical engineering aspects and describe in detail all the key aspects to be considered in the techno-economic assessment of wave energy converters. Written in an easy-to-understand style, the book answers questions relevant to readers of different backgrounds, from developers, private and public investors, to students and researchers. It is thereby a valuable resource for both newcomers and experienced practitioners in the wave energy sector.

Download or read book Modelling and Optimization of Wave Energy Converters written by Dezhi Ning and published by CRC Press. This book was released on 2022-07-28 with total page 384 pages. Available in PDF, EPUB and Kindle. Book excerpt: Wave energy offers a promising renewable energy source, however, technologies converting wave energy into useful electricity face many design challenges. This guide presents numerical modelling and optimization methods for the development of wave energy converter technologies, from principles to applications. It covers the development status and perspectives of wave energy converter systems; the fundamental theories on wave power absorption; the modern wave energy converter concepts including oscillating bodies in single and multiple degree of freedom and oscillating water column technologies; and the relatively hitherto unexplored topic of wave energy harvesting farms. It can be used as a specialist student textbook as well as a reference book for the design of wave energy harvesting systems, across a broad range of disciplines, including renewable energy, marine engineering, infrastructure engineering, hydrodynamics, ocean science, and mechatronics engineering. The Open Access version of this book, available at www.routledge.com has been made available under a Creative Commons Attribution-Non Commercial-No Derivatives 4.0 license.

Download or read book Hydrodynamic and Control Optimization for a Heaving Point Absorber Wave Energy Converter written by Siya Jin and published by . This book was released on 2019 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book OpenFOAM written by J. Miguel Nóbrega and published by Springer. This book was released on 2019-01-24 with total page 536 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book contains selected papers of the 11th OpenFOAM® Workshop that was held in Guimarães, Portugal, June 26 - 30, 2016. The 11th OpenFOAM® Workshop had more than 140 technical/scientific presentations and 30 courses, and was attended by circa 300 individuals, representing 180 institutions and 30 countries, from all continents. The OpenFOAM® Workshop provided a forum for researchers, industrial users, software developers, consultants and academics working with OpenFOAM® technology. The central part of the Workshop was the two-day conference, where presentations and posters on industrial applications and academic research were shown. OpenFOAM® (Open Source Field Operation and Manipulation) is a free, open source computational toolbox that has a larger user base across most areas of engineering and science, from both commercial and academic organizations. As a technology, OpenFOAM® provides an extensive range of features to solve anything from complex fluid flows involving chemical reactions, turbulence and heat transfer, to solid dynamics and electromagnetics, among several others. Additionally, the OpenFOAM technology offers complete freedom to customize and extend its functionalities.

Download or read book Scaling of Point absorber Wave Energy Converter Hydrodynamics written by Curtis John Rusch and published by . This book was released on 2021 with total page 85 pages. Available in PDF, EPUB and Kindle. Book excerpt: Wave energy converters (WECs) are devices that generate mechanical or electrical power from the motion of ocean waves. Point absorber WECs react to the motion of the ocean waves at or near the surface, and have a characteristic surface expression of less than one tenth of a wavelength. Two-body, point absorber WECs rely on the reaction force produced by a submerged component, usually a heave plate, to capture power from ocean waves. This work is motivated by limited understanding of heave plate hydrodynamics, necessary to produce accurate WEC models. In oscillatory flow, drag and inertial forces experienced by flat plates and cylinders have been shown to vary with the Keulegan-Carpenter number. We demonstrate that this extends to an asymmetric hexagonal conic heave plate suitable for a point absorber WEC. The forces on three geometric scales of this plate were measured by forced oscillation experiments in quiescent water. From these measurements, phase-invariant and phase-dependent coefficients of drag and added mass are calculated using a Morison decomposition. For low amplitude oscillations, the total force experienced by the conic heave plate is well-described by phase-invariant coefficients that scale with the Keulegan-Carpenter number. However, for larger oscillations, maximum forces are better described by phase-dependent coefficients. Flow visualization is used to interpret the phase variations. We explore the role of heave plate topology on fluid reaction forces using three representative shapes: a hexagonal flat plate, a hexagonal conic with an open top, and the same with a closed top that encloses a fluid mass. We force each test article sinusoidally in a quiescent tank and decompose the reaction force using forms of the Morison equation for phase-invariant and phase-dependent parameterizations. We find that a flat plate generates 5.3 % more fluid reaction force than the open conic topology, and 21.4 % more than the enclosed conic. We also show that asymmetric topologies generate asymmetric reaction forces, but the magnitude of asymmetry is limited by nearly symmetric fluid inertia forces, which dominate over drag for these test articles. Additionally, we observe asymmetric vortex dynamics for the flat plate when the Keulegan-Carpenter number is between 1 and 2, accompanied by a shift in the phase of the peak force by about 7 % of the oscillation period. As a consequence of this shift, the hydrodynamic coefficients estimated from the phase-dependent Morison equation decomposition are asymmetric, suggesting that phase-dependent representations may not provide physical insight in some hydrodynamic regimes and that flat plates may have multiple reaction force profiles for a range of Keulegan-Carpenter numbers. Finally, we apply results from heave plate experiments to models of a two-body point absorber WEC. We approximate these hydrodynamics using three parameterizations: (1) as low-fidelity coefficients invariant across sea state, accurate only at the reference sea state, (2) mid-fidelity coefficients dependent on the oscillation amplitude, but invariant in phase, which accurately represent forces for small amplitude motions, and (3) high-fidelity coefficients dependent on both oscillation amplitude and phase, which represent hydrodynamic forces accurately for all oscillation amplitudes. As dynamical models of WECs often rely on a low-fidelity representation, it is important to understand how this practice impacts wave energy converter modelling and whether code bases should be extended to incorporate higher-fidelity representations of heave plate hydrodynamics. Here, we validate an analytical model for a two-body point absorber WEC against field data and a dynamical model. We then use the analytical model to evaluate the effect of these parameterizations on estimates of heave plate motion, tension between the float and heave plate, and electrical power output from the WEC. We find that predictions of electrical power output using mid-fidelity coefficients differ by up to 30 % from models using low-fidelity coefficients for regular waves ranging in height from 0.5 - 1.9 m. High-fidelity coefficients, however, yield less than a 5 % change when compared with mid-fidelity coefficients. This suggests that mid-fidelity coefficients can be important for accurate wave energy converter modeling, but the added complexity of high-fidelity coefficients yields little further benefit. We show similar, though less pronounced, trends in maximum tether tension, while heave plate motion has only a weak dependence on coefficient fidelity. Finally, we emphasize the importance of using experimentally derived added mass over that calculated from boundary element methods (another common practice for dynamical models), which can lead to substantial under-prediction of power output and peak tether tension. In total, this work experimentally characterizes the hydrodynamics of asymmetric heave plates across scale and topology, touches on the intricacies of vortex behavior in these experiments, and models two-body WECs using heave plate hydrodynamic parameterizations of varying fidelity to determine the impact on WEC behavior. This fills a gap in the literature in asymmetric heave plate hydrodynamics. This also provides the first characterization of the impact of enclosed fluid on the reaction force heave plates provide to point absorber WECs. Moreover, we provide guidance on the use of these hydrodynamic parameterizations to WEC modellers, assessing the changes seen in model behavior for low-, mid-, and high-fidelity hydrodynamic representations.

Download or read book Ocean Wave Energy Conversion written by Aurelien Babarit and published by Elsevier. This book was released on 2017-11-17 with total page 264 pages. Available in PDF, EPUB and Kindle. Book excerpt: The waves that animate the surface of the oceans represent a deposit of renewable energy that for the most part is still unexploited today. This is not for lack of effort, as for more than two hundred years inventors, researchers and engineers have struggled to develop processes and systems to recover the energy of the waves. While all of these efforts have failed to converge towards a satisfactory technological solution, the result is a rich scientific and technical literature as well as extensive and varied feedback from experience. For the uninitiated, this abundance is an obstacle. In order to facilitate familiarization with the subject, we propose in this work a summary of the state of knowledge on the potential of wave energy as well as on the processes and technologies of its recovery (wave energy converters). In particular, we focus on the problem of positioning wave energy in the electricity market, the development of wave energy conversion technologies from a historical perspective, and finally the energy performance of the devices. This work is aimed at students, researchers, developers, industry professionals and decision makers who wish to acquire a global perspective and the necessary tools to understand the field. Reviews the state of knowledge and developments on wave energy recovery Presents the history of wave energy recovery Classifies the various systems for recovering this type of energy

Download or read book Time domain Modeling of Heaving Point Absorber Wave Energy Converters Including Power Take off and Mooring written by Kelley Ruehl and published by . This book was released on 2011 with total page 73 pages. Available in PDF, EPUB and Kindle. Book excerpt: Wave energy conversion is still in its infancy, and in order for it to become a commercially viable technology, developers, investors and utilities need to estimate a Wave Energy Converter's (WEC's) performance for the wave climate of a potential installation site. With the goal of estimating a design's power output when subject to stochastic ocean waves, a time-domain modeling methodology was developed for point absorber WECs with arbitrary device geometry. This methodology uses the geometry's unique frequency-domain hydrodynamic response to determine the point absorber's time-domain impulse response functions. By implementing the point absorber's impulse response functions, time-domain equations of motion are defined and the WEC's heave displacement and velocity are solved for in a WEC Dynamics Model developed in MATLAB/Simulink. The modeling methodology is first validated for a single-body point absorber with complex geometry by comparison with experimental data. Then the methodology is applied to a two-body point absorber geometry that is representative of designs currently being pursued. The time-domain point absorber model is extended to include a hydraulic power take-off system model that estimates the wave energy converter's power output when subject to real ocean waves. Finally, results are presented from the combined WEC dynamics and hydraulic power take-off system model when subject to time-series wave surface elevation from NDBC Umpqua Offshore buoy 46229.

Download or read book Ocean Wave Energy written by Joao Cruz and published by Springer Science & Business Media. This book was released on 2007-12-22 with total page 435 pages. Available in PDF, EPUB and Kindle. Book excerpt: The authors of this timely reference provide an updated and global view on ocean wave energy conversion – and they do so for wave energy developers as well as for students and professors. The book is orientated to the practical solutions that this new industry has found so far and the problems that any device needs to face. It describes the actual principles applied to machines that convert wave power to electricity and examines state-of-the-art modern systems.

Download or read book Evaluation of Ocean Energy Conversion Based on Linear Generator Concepts written by Michael A. Stelzer and published by AuthorHouse. This book was released on 2012-07-03 with total page 169 pages. Available in PDF, EPUB and Kindle. Book excerpt: EVALUATION OF OCEAN-ENERGY CONVERSION BASED ON LINEAR GENERATOR CONCEPTS As the world continues to demand greater productivity and lifestyle enrichment through technological advancements, the demand for electrical power is predicted to escalate dramatically. Thus far, this increased demand has been primarily supplied from fossil fueled plants. Unfortunately, the burning of fossil fuels produce harmful carbon dioxide pollution as a by-product. It has been hypothesized that unless a clean, renewable, and efficient alternate source of energy is found soon, the world may either exhaust its supplies of energy-producing materials or drastically degrade its environment. However, motions that occur naturally, such as ocean waves, can play a significant role in generating environmentally safe and economically viable energy for human utilization. The focus of this work predicts the electrical power generation capabilities from a seabed mounted linear generator tethered to a floating buoy heaving under the influence of passing ocean surface waves. Mathematical models are introduced which simulate the oceans' surface conditions under both the regular (basic) and irregular (natural) wave regimes, the heave (vertical displacement) response for a floating buoy, and the resulting electrical output parameters of the linear generator. Within these models, various physical and electrical parameters are altered in an attempt to generate a greater output power for a given sea state condition, making the Wave Energy Converter (WEC) more efficient. It is shown theoretically that the buoy can be designed to have a greater heave response than that of the height of a passing wave resulting in an increase in generated power from the linear generator. Author Information: Dr. Michael A. Stelzer is a Certified Project Manager and Senior Electronic Technician with a Ph.D. in Electrical and Computer Engineering. During his career to date, Mr. Stelzer has published four additional educational titles and has been admitted into Cambridge Who's Who top 101 industry experts.

Download or read book Ocean Waves and Oscillating Systems written by Johannes Falnes and published by Cambridge University Press. This book was released on 2020-05-28 with total page 319 pages. Available in PDF, EPUB and Kindle. Book excerpt: Understand the absorption of energy from ocean waves by means of oscillating systems with this useful new edition. Essential for engineers, researchers, and graduate students, and an indispensable tool for those who work in this field.

Download or read book Hydrodynamics of Ocean Wave Energy Utilization written by David V. Evans and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 451 pages. Available in PDF, EPUB and Kindle. Book excerpt: The papers which follow were presented at an International Sym posium held in Lisbon from 8-11 July 1985 on the Hydrodynamics of Ocean Wave-Energy Utilization and sponsored by the Interna tional Union of Theoretical and Applied Mechanics. The subject of the Symposium embraced wave statistics, numerical methods, theoretical, experimental and field studies of wave energy devices. The idea of extracting useful energy from ocean waves continues to attract the curiosity of scientists and engineers in many parts of the world as the following papers indicate. Increasing ly the trend is towards smaller devices suitable for use near remote island communities where wave power, as an alternative to costly diesel fuel for electric generators, is already very competitive in economic terms. The decision to build two different prototype wave-power devices into the cliffs off Bergen in Norway has provided a welcome impetus to the field, stimulating a large amount of theoretical work on oscillating water column-type devices. In particular phase control methods - in which force and velocity of a rigid body, or pressure and volume flux across a turbine are matched in phase to achieve maximum power output - rightfully occupy a central place in the papers that follow. In addition to the established workers in the field, a new ge neration of wave-energy enthusiasts is emerging, learning from the mistakes of others and contributing exciting ideas of both a conceptual and practical nature.

Download or read book Marine Hydrodynamics 40th anniversary edition written by J. N. Newman and published by MIT Press. This book was released on 2018-01-26 with total page 450 pages. Available in PDF, EPUB and Kindle. Book excerpt: A textbook that offers a unified treatment of the applications of hydrodynamics to marine problems. The applications of hydrodynamics to naval architecture and marine engineering expanded dramatically in the 1960s and 1970s. This classic textbook, originally published in 1977, filled the need for a single volume on the applications of hydrodynamics to marine problems. The book is solidly based on fundamentals, but it also guides the student to an understanding of engineering applications through its consideration of realistic configurations. The book takes a balanced approach between theory and empirics, providing the necessary theoretical background for an intelligent evaluation and application of empirical procedures. It also serves as an introduction to more specialized research methods. It unifies the seemingly diverse problems of marine hydrodynamics by examining them not as separate problems but as related applications of the general field of hydrodynamics. The book evolved from a first-year graduate course in MIT's Department of Ocean Engineering. A knowledge of advanced calculus is assumed. Students will find a previous introductory course in fluid dynamics helpful, but the book presents the necessary fundamentals in a self-contained manner. The 40th anniversary of this pioneering book offers a foreword by John Grue. Contents Model Testing • The Motion of a Viscous Fluid • The Motion of an Ideal Fluid • Lifting Surfaces • Waves and Wave Effects • Hydrodynamics of Slender Bodies

Download or read book Wave Energy Devices written by Srinivasan Chandrasekaran and published by CRC Press. This book was released on 2022-04-19 with total page 273 pages. Available in PDF, EPUB and Kindle. Book excerpt: Designing offshore wave energy converter (WEC) devices requires a thorough understanding of many aspects of science and engineering, namely, wave hydrodynamics, wave-WEC interactions, mechanical design, analysis tools, and conducting experiments. This book provides the tools for understanding these complex systems and addresses the basic concepts of WECs through detailed analysis and design. A few devices developed and experimentally investigated are discussed in detail, some of which are considered highly novel and still in the preliminary stages of study in the existing literature. FEATURES Offers numerous detailed design methods and practical model studies Presents analysis of the dynamic response behavior of WECs based on experimental studies on scale models Covers the most recent and novel innovations in the field Includes a discussion of offshore wind farms as a green energy alternative and examines their conceptual development and design This book serves as a useful guide for both academicians and professionals in naval architecture and offshore engineering as well as in civil and structural engineering. In addition, it helps in the understanding of structural behavior in terms of risk criteria, efficiency, service life, and reliability. Readers will gain a comprehensive knowledge of the design and development of offshore wave energy devices and the preliminary design of offshore wind turbines, which are currently largely absent in the scientific literature.