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Sewan Park

Bio: Sewan Park is an academic researcher from Korean Ocean Research and Development Institute. The author has contributed to research in topics: Oscillating Water Column & Offshore wind power. The author has an hindex of 5, co-authored 21 publications receiving 85 citations.

Papers
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Journal ArticleDOI
TL;DR: The OES Wave Energy Conversion Modelling Task, which focused on the verification and validation of numerical models for simulating wave energy converters, is summarized, with a focus on investigating the impact of different levels of nonlinearities in the numerical models.
Abstract: 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 use of numerical models used in design as well as power performance assessment of WECs. To establish this confidence, the authors used different existing computational modelling tools to simulate given tasks to identify uncertainties related to simulation methodologies: (i) linear potential flow methods; (ii) weakly nonlinear Froude–Krylov methods; and (iii) fully nonlinear methods (fully nonlinear potential flow and Navier–Stokes models). This article summarizes the code-to-code task and code-to-experiment task that have been performed so far in this project, with a focus on investigating the impact of different levels of nonlinearities in the numerical models. Two different WECs were studied and simulated. The first was a heaving semi-submerged sphere, where free-decay tests and both regular and irregular wave cases were investigated in a code-to-code comparison. The second case was a heaving float corresponding to a physical model tested in a wave tank. We considered radiation, diffraction, and regular wave cases and compared quantities, such as the WEC motion, power output and hydrodynamic loading.

29 citations

Journal ArticleDOI
HaKun Jang1, Sewan Park, Moo-Hyun Kim1, Kyong-Hwan Kim, Keyyong Hong 
TL;DR: In this paper, the authors investigated the effect of heave-plate effects on the behavior of a multi-unit floating offshore wind turbine (MUFOWT) and found that the heave plates are effective in reducing heave and pitch motions and shift their natural frequencies with a minimal increase of mass.

18 citations

Journal ArticleDOI
02 Mar 2021-Energies
TL;DR: In this article, the authors present results for a breakwater-mounted Oscillating Water Column (OWC) device at scale 1:4 relative to a full-scale installation in a water depth of 12.8 m. The power-extracting air turbine is modeled by an orifice plate of 1-2% of the internal chamber surface area.
Abstract: This paper reports on an ongoing international effort to establish guidelines for numerical modeling of wave energy converters, initiated by the International Energy Agency Technology Collaboration Program for Ocean Energy Systems. Initial results for point absorbers were presented in previous work, and here we present results for a breakwater-mounted Oscillating Water Column (OWC) device. The experimental model is at scale 1:4 relative to a full-scale installation in a water depth of 12.8 m. The power-extracting air turbine is modeled by an orifice plate of 1–2% of the internal chamber surface area. Measurements of chamber surface elevation, air flow through the orifice, and pressure difference across the orifice are compared with numerical calculations using both weakly-nonlinear potential flow theory and computational fluid dynamics. Both compressible- and incompressible-flow models are considered, and the effects of air compressibility are found to have a significant influence on the motion of the internal chamber surface. Recommendations are made for reducing uncertainties in future experimental campaigns, which are critical to enable firm conclusions to be drawn about the relative accuracy of the numerical models. It is well-known that boundary element method solutions of the linear potential flow problem (e.g., WAMIT) are singular at infinite frequency when panels are placed directly on the free surface. This is problematic for time-domain solutions where the value of the added mass matrix at infinite frequency is critical, especially for OWC chambers, which are modeled by zero-mass elements on the free surface. A straightforward rational procedure is described to replace ad-hoc solutions to this problem that have been proposed in the literature.

11 citations

Journal ArticleDOI
TL;DR: In this article, a finite element method was applied to solve the potential flow around and inside an inclined oscillating-water-column (OWC) wave energy converter (WEC), and a turbine-chamber interaction was considered to take into account the pressure drop inside the OWC chamber.
Abstract: In this study, a time-domain numerical method based on three-dimensional potential flow was developed to analyze the hydrodynamic characteristics of an inclined oscillating-water-column (OWC) wave energy converter (WEC). A finite element method was applied to solve the potential flow around and inside the OWC chamber. A turbine–chamber interaction was considered to take into account the pressure drop inside the OWC chamber, which is a nonlinear function of airflow speed via turbine operation. The instantaneous pressure drop was updated on the free-surface boundary condition inside the chamber in the time-domain to account for the coupling effect between the turbine and the chamber. The present numerical method was verified by comparing it with the model test results. The hydrodynamic characteristics of an inclined OWC chamber in terms of potential flow, such as the water column motion and the three-dimensional flow distribution around the chamber, were investigated. In terms of hydrodynamic performance, the energy conversion efficiency of the chamber showed a nonlinear response characteristic dependent on the incident wave height. In addition, numerical calculations were carried out to clarify the relationship between the main geometric parameters and the hydrodynamic response of the inclined OWC chamber.

9 citations


Cited by
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Journal ArticleDOI
TL;DR: The power take-off systems of the wave energy converters (WEC) based on the different working methods of their power take off systems are reviewed, showing that the mechanical direct drive system is the most popular.

143 citations

Journal ArticleDOI
29 Sep 2017-Energies
TL;DR: In this paper, an extended overview of the marine renewable energy in the Mediterranean Sea is provided as regards current status, potential problems, challenges, and perspectives of development An integrated and holistic approach is necessary for the economic viability and sustainability of MARE projects; this approach comprises three different frameworks, not always aligned, i.e., geotechnical/engineering, socio-economic, and environmental/ecological frameworks.
Abstract: In this work, an extended overview of the marine renewable energy in the Mediterranean Sea is provided as regards current status, potential problems, challenges, and perspectives of development An integrated and holistic approach is necessary for the economic viability and sustainability of marine renewable energy projects; this approach comprises three different frameworks, not always aligned, ie, geotechnical/engineering, socio-economic, and environmental/ecological frameworks In this context, the geomorphological, climatological, socio-economic, and environmental/ecological particularities of the Mediterranean basin are discussed, as they constitute key issues of the spatial context in which marine renewable energy projects are to be implemented General guidelines for the sustainable development of marine renewable energy in the Mediterranean are also provided

93 citations

Journal ArticleDOI
TL;DR: In this article, a numerical model was developed based on potential flow theory with viscous correction in frequency domain to investigate the hydrodynamic performance of a hybrid system consisting of a floating platform and multiple heaving WECs.

72 citations

Journal ArticleDOI
TL;DR: A critical overview of the state-of-the-art in wave energy device geometry optimisation is provided, comparing and contrasting various optimisation approaches, and attempting to detail the current limitations preventing further progress, and convergence, in the development of optimal wave energy technology.

50 citations

Journal ArticleDOI
TL;DR: The aim of the present study is to provide a multidisciplinary state of the art review on, whenever possible, multi-purpose platforms, complementing it with single-purpose and/or single discipline literature reviews when not possible.

46 citations