Giuseppe Giorgi

Giuseppe Giorgi
Politecnico di Torino | polito · DIMEAS - Department of Mechanical and Aerospace

PhD - Mechanical and Ocean Engineering

About

65
Publications
22,914
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Introduction
Giuseppe Giorgi currently works at the Department of Mechanical and Aerospace Engineering, at Politecnico di Torino. Giuseppe does research in Mechanical Engineering and Ocean Engineering, focusing on nonlinear modelling and optimization of wave energy converters.
Additional affiliations
February 2019 - April 2021
Politecnico di Torino
Position
  • PostDoc Position

Publications

Publications (65)
Article
Full-text available
Motivated by the relevance of so-called nonlinear Froude–Krylov (FK) hydrodynamic effects in the accurate dynamical description of wave energy converters (WECs) under controlled conditions, and the apparent lack of a suitable control framework effectively capable of optimally harvesting ocean wave energy in such circumstances, we present, in this p...
Article
Full-text available
This study pertains to analysing the dynamical behaviour of a floating body undergoing parametric resonances. A simple vertical cylinder, representing a classical spar-buoy, is considered, limiting its motion to heave and pitch degrees of freedom. Its geometry and mass distribution are chosen such that a 2:1 ratio of heave to pitch/roll natural fre...
Cover Page
Full-text available
The Marine Offshore Renewable Energy Lab (MOREnergy Lab) in collaboration with the Centre for Ocean Energy Research (COER) Maynooth, will host the 7 th Wave Energy Workshop with invited experts from the ocean energy academic, industrial and policy community. The workshop, usually held in Maynooth, Co. Kildare, Ireland is moving to Turin, Italy this...
Article
Full-text available
This work presents the Water Energy Point Absorber (WEPA), which is a heaving single-buoy point absorber optimized for a specific site off the west coast of Sardinia Island. The aim of the study is to present the optimization process undertaken to identify the best configuration in terms of performance and cost. The optimization is carried out than...
Chapter
The ocean is the largest untapped energy site in the world and the recent decades have shown promising developments towards the wave energy converters (WEC). Among the problems related to the WECs are surely the optimal control strategy and the reliability in extreme waves conditions, and certainly also the tuning of the device, which due to the in...
Article
Full-text available
In recent years, we have been witnessing great interest and activity in the field of wave energy converters’ (WECs) development, striving for competitiveness and economic viability via increasing power conversion while decreasing costs and ensuring survivability [...]
Article
Full-text available
Computationally fast and accurate mathematical models are essential for effective design, optimization, and control of wave energy converters. However, the energy-maximising control strategy, essential for reaching economic viability, inevitably leads to the violation of linearising assumptions, so the common linear models become unreliable and pot...
Conference Paper
Full-text available
Given the relevance of control-oriented models in optimal control design for wave energy converters (WECs), this paper presents a data-driven technique to achieve nonlinear model reduction by moment-matching for the ISWEC device, a device originally developed at the Politecnico di Torino. The presented model reduction technique is capable of provid...
Conference Paper
Full-text available
In the wave energy conversion field, simulation tools are crucial for effective converter and controller design, but are often prone to become very case-specific, in both structure and parameter selection. This is due to majorly different working principles and diverse importance of nonlinear effects, at times requiring ad-hoc modelling approaches....
Conference Paper
Full-text available
Floating wave energy converters usually exhibit significant nonlinear behaviour, especially due to large variations of the wetted surface even during normal operation. In fact, in order to maximise energy extraction , the system is driven as far away from equilibrium as allowed by technical constraints. Consequently, the reliability of linear model...
Article
Full-text available
Energy harvesting technologies are attracting increasing attention in the last decades, mainly thanks to the rapid advancement of sensors miniaturization, wireless sensors network, the internet of things, and the growing awareness on energy efficiency. The main objective of current research on energy harvesters is to enlarge the natural response ba...
Article
Recent years have witnessed an increasing interest in energy harvesting in order to improve the overall power efficiency and making sensors self-sufficient and durable. One major potential source of energy is related to vibrations, ubiquitous in every mechanical system. In order to increase net harvested power and absorption frequency bandwidth, no...
Code
This toolbox and attached document purport to describe in detail the mathematical framework for a computationally efficient computation of nonlinear Froude-Krylov forces (NLFK) in 6 degrees of freedom (DoFs) for axisymmetric floating objects and 3 in DoFs for prismatic floaters. Additionally, the document also acts as a reference manual to a set of...
Chapter
In recent years, wave renewable energy is becoming established as one of the crucial components of a diversified and successful energy mix. The Inertial Sea Wave Energy Converter (ISWEC) is a mature technology, especially designed for closed seas, as the Mediterranean Sea, which has already been deployed in full-scale. At this stage of development,...
Article
Full-text available
Wave energy converters (WECs) inherently require appropriate control system technology to ensure maximum energy absorption from ocean waves, consequently reducing the associated levelised cost of energy and facilitating their successful commercialisation. Regardless of the control strategy, the definition of the control problem itself depends upon...
Conference Paper
Full-text available
The Spar-buoy is an axisymmetric floating oscillating water column (OWC) wave energy converter. Minimizing the cost of energy requires an efficient power conversion while limiting costs and ensuring survivability. A critical and challenging design problem is the parsimonious definition of a compliant mooring system, assuring sea-keeping but with sm...
Article
The paper presents results from the Collaborative Computational Project in Wave Structure Interaction (CCP-WSI) Blind Test Series 2. Without prior access to the physical data, participants, with numerical methods ranging from low-fidelity linear models to fully nonlinear Navier-Stokes (NS) solvers, simulate the interaction between focused wave even...
Code
Full-text available
This document purports to describe in detail the mathematical framework for a computationally efficient computation of nonlinear Froude-Krylov forces (NLFK) in 6 degrees of freedom (DoFs) for axisymmetric floating objects. Additionally, this document also acts as a reference manual to a set of Matlab scripts, forming a demonstration toolbox to show...
Research Proposal
Full-text available
In recent years we are witnessing a great interest and activity in the field of wave energy converters (WECs) development, striving for competitiveness and economic viability via increasing power conversion while decreasing costs and ensuring survivability. In the community the consensus is that both optimization and control are sine qua non condit...
Article
Full-text available
The mooring system of floating wave energy converters (WECs) has a crucial impact on power generation efficiency, cost of delivered energy, proper operation, reliability and survivability. An effective design, addressing such competing objectives, requires appropriate mathematical models to predict mooring loads and dynamic response. However, conve...
Article
Full-text available
The wave energy sector has faced enormous technological improvements over the last five decades, however, due to the complexity of the hydrodynamic processes, current numerical models still have limitations in predicting relevant phenomena. In particular, floating spar-type wave energy converters are prone to large undesirable roll and pitch amplit...
Article
Full-text available
Mathematical models are essential for the design and control of offshore systems, to simulate the fluid-structure interactions and predict the motions and the structural loads. In the development and derivation of the models, simplifying assumptions are normally required, usually implying linear kinematics and hydrodynamics. However, while the assu...
Article
Full-text available
Representative models of the nonlinear behavior of floating platforms are essential for their successful design, especially in the emerging field of wave energy conversion where nonlinear dynamics can have substantially detrimental effects on the converter efficiency. The spar buoy, commonly used for deep-water drilling, oil and natural gas extract...
Article
Full-text available
Although sea and ocean waves have been widely acknowledged to have the potential of providing sustainable and renewable energy, the emergence of a self-sufficient and mature industry is still lacking. An essential condition for reaching economic viability is to minimise the cost of electricity, as opposed to simply maximising the converted energy a...
Article
Full-text available
The hydrodynamic investigation of a hull's performance is a key aspect when designing a new prototype, especially when it comes to a competitive/racing environment. This paper purports to perform a fully nonlinear unsteady Reynolds Averaged Navier-Stokes (RANS) simulation to predict the motion and hydrodynamic resistance of a sailboat, thus creatin...
Article
Full-text available
During the optimization phase of a wave energy converter (WEC), it is essential to be able to rely on a model that is both fast and accurate. In this regard, Computational Fluid Dynamic (CFD) with Reynolds Averaged Navier–Stokes (RANS) approach is not suitable for optimization studies, given its computational cost, while methods based on potential...
Article
Full-text available
A proper design of the mooring systems for Wave Energy Converters (WECs) requires an accurate investigation of both operating and extreme wave conditions. A careful analysis of these systems is required to design a mooring configuration that ensures station keeping, reliability, maintainability, and low costs, without affecting the WEC dynamics. In...
Article
Results from the CCP-WSI Blind Test Series 3 are presented. Participants, with numerical methods, ranging from low-fidelity linear models to high-fidelity Navier–Stokes (NS) solvers, simulate the interaction between focused waves and floating structures without prior access to the physical data. The waves are crest-focused New Waves with various cr...
Article
Full-text available
The wave energy sector is experiencing lively years of conceptual innovation and technological advances. Among the great variety of candidates, only a few are going to be able to reach maturity and, eventually, industrial feasibility and competitiveness. The essential requisite for success is the continuous innovation in response to the incremental...
Article
Full-text available
Although it is widely accepted that accurate modeling of wave energy converters is essential for effective and reliable design, it is often challenging to define an accurate model which is also fast enough to investigate the design space or to perform extensive sensitivity analysis. In fact, the required accuracy is usually brought by the inclusion...
Article
Full-text available
The International Energy Agency Technology Collaboration Programme for Ocean Energy Systems (OES) initiated the OES Wave Energy Conversion Modelling Task, which focused on the verification and validation of numerical models for simulating wave energy converters (WECs). The long-term goal is to assess the accuracy of and establish confidence in the...
Conference Paper
Full-text available
Cummins' equation is commonly used to describe the motion of Wave Energy Converters (WECs), where the radiation force is characterised by a convolution operation. The computational effort associated with the solution of the convo-lution term, often represents a drawback for e.g. optimisation or exhaustive-search studies. To overcome this disadvanta...
Conference Paper
Full-text available
We present in this paper a moment-matching method to compute a parametric approximation of the input-output (force-to-motion) response of a multiple Degree of Freedom (DoF) Wave Energy Converter (WEC), based on the algorithm presented in [1]. This method allows the user to select a set of interpolation frequencies where the approximating model exac...
Thesis
Full-text available
One of the major challenges facing modern industrialized countries is the provision of energy: traditional sources, mainly based on fossil fuels, are not only growing scarcer and more expensive, but are also irremediably damaging the environment. Renewable and sustainable energy sources are attractive alternatives that can substantially diversify t...
Code
Cummins' equation is commonly used to describe the motion of Wave Energy Converters (WECs), where the radiation force is characterised by a convolution operation. The computational effort associated with the solution of the convolution term often represents a drawback for e.g. optimisation or exhaustive-search studies. To overcome this disadvantage...
Chapter
Full-text available
Wave energy conversion is an active field of research, aiming to harness the vast amounts of energy present in ocean waves. An essential development trajectory towards an economically competitive wave energy converter (WEC) requires early device experimentation and refinement using numerical tools. OpenFOAM\(^{\textregistered }\) is proving to be a...
Article
Full-text available
Wave energy devices are designed, and controlled, to be extremely responsive to incoming wave excitation, hence, maximising power absorption. Due to the consequent large motion excursions, highly nonlinear behaviour is likely to occur, especially in relation to variations in wetted surface. Moreover, nonlinearities may induce parametric instability...
Conference Paper
Full-text available
Parametric resonance is a highly nonlinear phenomenon, difficult to model and foresee , with often detrimental consequences on the power production efficiency of wave energy converters. Parametric excitation, due to time-varying parameters of the system, activates an internal excitation mechanism, which diverts part of the energy from the principal...
Conference Paper
Full-text available
Wave energy devices are designed, and controlled, in order to be extremely responsive to incoming wave excitation, hence maximising power absorption. Due to the consequent large motion excursions, highly nonlinear behaviour is likely to occur, especially in relation to variations in wetted surface. Moreover, nonlinearities may induce parametric ins...
Conference Paper
Full-text available
Accurate and computationally efficient mathematical models are fundamental for designing, optimizing, and controlling wave energy converters. Wave energy devices are likely to exhibit significant nonlinear behaviour, over their full operational envelope, so that nonlinear models may become indispensable. Froude-Krylov nonlinearities are of great im...
Article
Full-text available
High accuracy, with low computational time is likely to be a fundamental requirement for mathematical models for wave energy converters, in order to be effective tools for reliable motion prediction and power production assessment, device and controller design, and load estimation. Wave energy converters are particularly prone to complex nonlinear...
Conference Paper
Full-text available
The concept of resonance is well known in the study of wave energy converters (WECs), with the natural fre- quency of WECs typically designed to resonate with the external excitation provided by the input wave field. Para- metric resonance, on the other hand, has received very little attention, likely due to the complexity of the mod- els required...
Chapter
Full-text available
Wave energy conversion is an active field of research, aiming to harness the vast amounts of energy present in ocean waves. An essential development tra-jectory towards an economically competitive wave energy converter (WEC) requires early device experimentation and refinement using numerical tools. OpenFOAM is proving to be a useful numerical tool...
Article
Full-text available
http://rdcu.be/vm3Y Two of the most common modes of oscillation of single degree of freedom wave energy converters are heave and surge, which are, respectively, exploited by heaving point absorbers (HPAs), and oscillating wave surge converters (OWSCs). Given major hydrodynamic differences between HPAs and OWSC, different nonlinear forces may be mo...
Article
Full-text available
Online file: http://rdcu.be/Dzw4 Due to their computational convenience, linear mathematical models for wave energy converters are usually employed. Including nonlinearities may improve the accuracy of the results, but often at the price of an additional computational and complexity burden, which can be justified only if nonlinearities are signif...
Article
Full-text available
Wave energy devices are designed, and controlled, in order to be extremely responsive to incoming wave excitation, hence maximising power absorption. Due to the consequent large motion excursions, highly nonlinear behaviour is likely to occur, especially in relation to variations in wetted surface. Moreover, nonlinearities may induce parametric ins...
Article
Control of wave energy converters (WECs) has been very often limited to hydrodynamic control to absorb the maximum energy possible from ocean waves. This generally ignores or significantly simplifies the performance of real power take-off (PTO) systems. However, including all the required dynamics and constraints in the control problem may consider...
Article
Designing, optimizing and controlling a wave energy converter requires the construction of a mathematical model in order to simulate the behaviour of the device. Given the nonlinear nature of fluid-structure interactions, the definition of the model is not straightforward and should take into account the specific application it is intended for. Two...
Conference Paper
Full-text available
Due to their computational convenience, mathematical models for wave energy converters are usually linear. Including nonlinearities may improve the accuracy of the results, but often at the price of an additional computational and complexity burden, which can be justified only if nonlinearities are significant. One of the sources of nonlinearity in...
Conference Paper
Full-text available
Viscous drag forces in mathematical models for wave energy converters are usually modelled by means of a term based on the Morison equation. Due to large relative velocities, induced by control strategies in order to increase the power absorption, viscous losses can have a high impact on the model accuracy and, in turn, on the model-based power opt...
Article
Full-text available
http://rdcu.be/nx6r Most wave energy converters (WECs) are described by linear mathematical models, based on the main assumption of small amplitudes of motion. Notwithstanding the computational convenience, linear models can become inaccurate when large motions occur. On the other hand, nonlinear models are often time consuming to simulate, while m...
Conference Paper
Full-text available
Numerical models for heaving buoy wave energy converters are a fundamental tool for device design and optimization , power production assessment and model-based controller design. Ideally, models are required to be easy to implement, simple, accurate and computationally efficient. Unfortunately, such features are often conflicting and a compromise...
Conference Paper
Full-text available
Two of the most common modes of oscillation of single degree of freedom wave energy converters are heave and surge, which are respectively exploited by heaving point absorbers (HPAs) and oscillating surge converters (OSCs). Notwithstanding essential hydrodynamic differences, both devices are very often described by the same linear model structure....