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Ioannis K. Chatjigeorgiou
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4 records found
1
Book chapter
(2022)
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Eva Loukogeorgaki, Constantine Michailides, G. Lavidas, S. Saeidtehrani, Ioannis K. Chatjigeorgiou
In this paper, we assess numerically the loads applied on PAs of optimally-arranged linear arrays in front of a bottom-mounted vertical wall of finite length under normal operating conditions. The arrays, maximizing the yearly absorbed energy, consist of five, identical, oblate spheroidal heaving PAs and are deployed at three near-shore sites in the Aegean Sea, Greece. The PAs are assumed to be attached on the wall via connection configurations restraining all rigid-body modes except heave. A spectral analysis is performed to quantify loads. The corresponding transfer functions are obtained from a frequency-based hydrodynamic model that solves the diffraction/radiation problem of the multi-body arrangement in the presence of the wall. Results, focusing on surge and sway restraining loads, are, initially, presented for regular waves and, then, for normal operating conditions (irregular waves), highlighting the effect of the arrays’ layouts and of the local wave conditions on the restraining loads. Comparison is also made with equally-spaced arrays to reveal potential positive effects of optimum layouts on structural integrity related issues.
...
In this paper, we assess numerically the loads applied on PAs of optimally-arranged linear arrays in front of a bottom-mounted vertical wall of finite length under normal operating conditions. The arrays, maximizing the yearly absorbed energy, consist of five, identical, oblate spheroidal heaving PAs and are deployed at three near-shore sites in the Aegean Sea, Greece. The PAs are assumed to be attached on the wall via connection configurations restraining all rigid-body modes except heave. A spectral analysis is performed to quantify loads. The corresponding transfer functions are obtained from a frequency-based hydrodynamic model that solves the diffraction/radiation problem of the multi-body arrangement in the presence of the wall. Results, focusing on surge and sway restraining loads, are, initially, presented for regular waves and, then, for normal operating conditions (irregular waves), highlighting the effect of the arrays’ layouts and of the local wave conditions on the restraining loads. Comparison is also made with equally-spaced arrays to reveal potential positive effects of optimum layouts on structural integrity related issues.
Conference paper
(2021)
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Eva Loukogeorgaki, Constantine Michailides, G. Lavidas, Ioannis K. Chatjigeorgiou
In this paper, we determine optimum layouts of a cluster of oblate spheroidal heaving point absorbers in front of a wall, that maximize the annual averaged power absorbed by the cluster, while satisfying specific spatial constraints. An iterative optimization process is developed by coupling a hydrodynamic model with a genetic algorithms solver. Optimization is performed for three near-shore sites in the Aegean Sea, Greece. Optimum layouts are obtained considering part of or the whole wall length, available for the PAs’ sitting. The effect of the incident wave direction on the optimum layouts’ formation and the absorbed power is also assessed. Finally, the dependence of the maximized absorbed power upon the deployment site is illustrated.
...
In this paper, we determine optimum layouts of a cluster of oblate spheroidal heaving point absorbers in front of a wall, that maximize the annual averaged power absorbed by the cluster, while satisfying specific spatial constraints. An iterative optimization process is developed by coupling a hydrodynamic model with a genetic algorithms solver. Optimization is performed for three near-shore sites in the Aegean Sea, Greece. Optimum layouts are obtained considering part of or the whole wall length, available for the PAs’ sitting. The effect of the incident wave direction on the optimum layouts’ formation and the absorbed power is also assessed. Finally, the dependence of the maximized absorbed power upon the deployment site is illustrated.
Conference paper
(2021)
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G. Lavidas, Eva Loukogeorgaki, Constantine Michailides, Ioannis K. Chatjigeorgiou
Wave Energy Converters (WEC) have seen a wide variety of innovations capable to harness the vast untapped energy source of the seas. This wide range of WECs often has varied applicability and power production capabilities, making the selection of a device overwhelming. These uncertainties are increased when
considering the interactions and suitability of the device with local metocean conditions, and the impacts to long-term reliable operation. The study focuses on the Mediterranean region and presents a comprehensive approach
in selecting a WEC, using a novel Selection Index for Wave Energy Deployments (SIWED), which accounts for resource, extreme events, power production capabilities, reducing uncertainties and biases. As a case study our
approach explores: (i) the viability of WECs at milder resource (ii) the use of SIWED to select the “optimal” location and (iii) an approach to optimise considering the multi-faceted resource impacts. The study provides
a comprehensive assessment of the “hidden” benefits of wave energy in the Mediterranean and its methodology is universally replicable. Finally, a discussion and overview on the importance of this interdisciplinary method for WEC
deployments is underlined. ...
considering the interactions and suitability of the device with local metocean conditions, and the impacts to long-term reliable operation. The study focuses on the Mediterranean region and presents a comprehensive approach
in selecting a WEC, using a novel Selection Index for Wave Energy Deployments (SIWED), which accounts for resource, extreme events, power production capabilities, reducing uncertainties and biases. As a case study our
approach explores: (i) the viability of WECs at milder resource (ii) the use of SIWED to select the “optimal” location and (iii) an approach to optimise considering the multi-faceted resource impacts. The study provides
a comprehensive assessment of the “hidden” benefits of wave energy in the Mediterranean and its methodology is universally replicable. Finally, a discussion and overview on the importance of this interdisciplinary method for WEC
deployments is underlined. ...
Wave Energy Converters (WEC) have seen a wide variety of innovations capable to harness the vast untapped energy source of the seas. This wide range of WECs often has varied applicability and power production capabilities, making the selection of a device overwhelming. These uncertainties are increased when
considering the interactions and suitability of the device with local metocean conditions, and the impacts to long-term reliable operation. The study focuses on the Mediterranean region and presents a comprehensive approach
in selecting a WEC, using a novel Selection Index for Wave Energy Deployments (SIWED), which accounts for resource, extreme events, power production capabilities, reducing uncertainties and biases. As a case study our
approach explores: (i) the viability of WECs at milder resource (ii) the use of SIWED to select the “optimal” location and (iii) an approach to optimise considering the multi-faceted resource impacts. The study provides
a comprehensive assessment of the “hidden” benefits of wave energy in the Mediterranean and its methodology is universally replicable. Finally, a discussion and overview on the importance of this interdisciplinary method for WEC
deployments is underlined.
considering the interactions and suitability of the device with local metocean conditions, and the impacts to long-term reliable operation. The study focuses on the Mediterranean region and presents a comprehensive approach
in selecting a WEC, using a novel Selection Index for Wave Energy Deployments (SIWED), which accounts for resource, extreme events, power production capabilities, reducing uncertainties and biases. As a case study our
approach explores: (i) the viability of WECs at milder resource (ii) the use of SIWED to select the “optimal” location and (iii) an approach to optimise considering the multi-faceted resource impacts. The study provides
a comprehensive assessment of the “hidden” benefits of wave energy in the Mediterranean and its methodology is universally replicable. Finally, a discussion and overview on the importance of this interdisciplinary method for WEC
deployments is underlined.
Journal article
(2021)
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Eva Loukogeorgaki, Constantine Michailides, G. Lavidas, Ioannis K. Chatjigeorgiou
The present paper focuses on the determination of optimum layouts for linear arrays of heaving Wave Energy Converters (WECs) in front of a vertical wall. Optimum layouts maximize the annual averaged absorbed energy at a given marine site and satisfy spatial constraints. For achieving this goal, we developed an efficient optimization numerical framework, where a genetic algorithm solver is appropriately coupled with a frequency-domain hydrodynamic model, while, furthermore, a numerical wave model is utilized to determine the local wave climate conditions at the site of interest. The context is applied for an array of five semi-immersed, oblate spheroidal heaving WECs deployed at five near-shore sites of mild wave environments in the Aegean Sea, Greece. For each site, different optimization cases are solved, facilitating the investigation of different aspects of the examined problem. The largest annual energy absorption ability is observed for optimum layouts, characterized by the placement of the array close to the wall and the formation of clusters of closely-positioned WECs near the wall edges. Compared to arrays employed at sites in south-eastern Aegean, optimally-arranged arrays at central Aegean locations showed reduced energy absorption ability due to milder local wave conditions and/or the existence of quite limited water depths.
...
The present paper focuses on the determination of optimum layouts for linear arrays of heaving Wave Energy Converters (WECs) in front of a vertical wall. Optimum layouts maximize the annual averaged absorbed energy at a given marine site and satisfy spatial constraints. For achieving this goal, we developed an efficient optimization numerical framework, where a genetic algorithm solver is appropriately coupled with a frequency-domain hydrodynamic model, while, furthermore, a numerical wave model is utilized to determine the local wave climate conditions at the site of interest. The context is applied for an array of five semi-immersed, oblate spheroidal heaving WECs deployed at five near-shore sites of mild wave environments in the Aegean Sea, Greece. For each site, different optimization cases are solved, facilitating the investigation of different aspects of the examined problem. The largest annual energy absorption ability is observed for optimum layouts, characterized by the placement of the array close to the wall and the formation of clusters of closely-positioned WECs near the wall edges. Compared to arrays employed at sites in south-eastern Aegean, optimally-arranged arrays at central Aegean locations showed reduced energy absorption ability due to milder local wave conditions and/or the existence of quite limited water depths.