TY - CONF AU - Giorgi, Giuseppe AU - Davidson, Joshua Patrick AU - Habib, Giuseppe AU - Bracco, Giovanni AU - Mattiazzo, Giuliana AU - Kalmár-Nagy, Tamás TI - Nonlinear kinematics of a moored axisymmetric wave energy converter T2 - ENOC 2022: Book of abstracts PY - 2022 SP - 842 EP - 849 PG - 8 UR - https://m2.mtmt.hu/api/publication/33561603 ID - 33561603 LA - English DB - MTMT ER - TY - CONF AU - Davidson, Joshua Patrick AU - Karimov, Mirlan AU - Habib, Giuseppe AU - Kalmár-Nagy, Tamás TI - Parametric resonance in floating bodies - Comparing monochromatic and polychromatic input waves T2 - ENOC 2022: Book of abstracts PY - 2022 SP - 936 EP - 937 PG - 2 UR - https://m2.mtmt.hu/api/publication/33561597 ID - 33561597 LA - English DB - MTMT ER - TY - JOUR AU - Davidson, Joshua Patrick AU - Kalmár-Nagy, Tamás AU - Habib, Giuseppe TI - Parametric excitation suppression in a floating cylinder via dynamic vibration absorbers: a comparative analysis JF - NONLINEAR DYNAMICS J2 - NONLINEAR DYNAM VL - 110 PY - 2022 SP - 1081 EP - 1108 PG - 28 SN - 0924-090X DO - 10.1007/s11071-022-07710-1 UR - https://m2.mtmt.hu/api/publication/33039229 ID - 33039229 N1 - Department of Fluid Mechanics, Faculty of Mechanical Engineering, Budapest University of Technology and Economics, Budapest, Hungary Department of Applied Mechanics, Faculty of Mechanical Engineering, MTA-BME Lendület “Momentum” Global Dynamics Research Group Budapest University of Technology and Economics, Budapest, Hungary Correspondence Address: Davidson, J.; Department of Fluid Mechanics, Hungary; email: davidson@ara.bme.hu AB - Parametric excitation in the pitch/roll degrees of freedom (DoFs) can induce dynamic instability in floating cylinder-type structures such as spar buoys, floating offshore wind or wave energy converters. At certain frequency and amplitude ranges of the input waves, parametric coupling between the heave and pitch/roll DoFs results in undesirable large amplitude rotational motion. One possible remedy to mitigate the existence of parametric resonance is the use of dynamic vibration absorbers. Two prominent types of dynamic vibration absorbers are tuned mass dampers (TMDs) and nonlinear energy sinks (NESs), which have contrasting properties with regard to their amplitude and frequency dependencies when absorbing kinetic energy from oscillating bodies. This paper investigates the suppression of parametric resonance in floating bodies utilizing dynamic vibration absorbers, comparing the performance of TMDs against NESs for a test case considering a floating vertical cylinder. In addition to the type of dynamic vibration absorber utilized, the paper also examines the DoF which it acts on, comparing the benefits between attaching the vibration absorber to the primary (heave) DoF or the secondary (pitch) DoF. The results show that the TMD outperforms the NES and that it is more effective to attach the vibration absorber to the heave DoF when eliminating parametric resonance in the pitch DoF. LA - English DB - MTMT ER - TY - JOUR AU - Habib, Giuseppe AU - Giorgi, Giuseppe AU - Davidson, Joshua Patrick TI - Coexisting attractors in floating body dynamics undergoing parametric resonance JF - ACTA MECHANICA J2 - ACTA MECH VL - 233 PY - 2022 SP - 2351 EP - 2367 PG - 17 SN - 0001-5970 DO - 10.1007/s00707-022-03225-3 UR - https://m2.mtmt.hu/api/publication/32845151 ID - 32845151 N1 - Export Date: 7 June 2022 CODEN: AMHCA Correspondence Address: Habib, G.; Department of Applied Mechanics, Hungary; email: habib@mm.bme.hu AB - 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 frequency makes the spar-buoy prone to parametric resonance. The system is then studied by the shooting method, combined with a pseudo-arclength continuation, and the harmonic balance procedure. Results show that an extensive bistable region exists, where stable parametric resonance coexists with a regular resonance response. The analysis also unveiled the existence of stable quasiperiodic motions existing in correspondence of both pitch and heave resonance. Results are qualitatively validated using a model based on the explicit nonlinear Froude–Krylov force calculation. LA - English DB - MTMT ER - TY - CONF AU - Windt, C. AU - Davidson, Joshua Patrick AU - Faedo, N. AU - Penalba, M. AU - Ringwood, J.V. TI - On the Importance of High–Fidelity Numerical Modelling of Ocean Wave Energy Converters under Controlled Conditions T2 - Floating Offshore Energy Devices PB - Materials Research Forum LLC PY - 2022 SP - 31 EP - 38 PG - 8 DO - 10.21741/9781644901731-5 UR - https://m2.mtmt.hu/api/publication/32753258 ID - 32753258 LA - English DB - MTMT ER - TY - JOUR AU - Lelkes, János AU - Davidson, Joshua Patrick AU - Kalmár-Nagy, Tamás TI - Modelling of Parametric Resonance for Heaving Buoys with Position-Varying Waterplane Area JF - JOURNAL OF MARINE SCIENCE AND ENGINEERING J2 - J MAR SCI ENG VL - 9 PY - 2021 IS - 11 PG - 24 SN - 2077-1312 DO - 10.3390/jmse9111162 UR - https://m2.mtmt.hu/api/publication/32472076 ID - 32472076 LA - English DB - MTMT ER - TY - JOUR AU - Ransley, Edward J. AU - Brown, Scott A. AU - Hann, Martyn AU - Greaves, Deborah M. AU - Windt, Christian AU - Ringwood, John AU - Davidson, Joshua Patrick AU - Schmitt, Pal AU - Yan, Shiqiang AU - Wang, Junxian X. AU - Wang, Jinghua H. AU - Ma, Qingwei AU - Xie, Zhihua AU - Giorgi, Giuseppe AU - Hughes, Jack AU - Williams, Alison AU - Masters, Ian AU - Lin, Zaibin AU - Chen, Hao AU - Qian, Ling AU - Ma, Zhihua AU - Chen, Qiang AU - Ding, Haoyu AU - Zang, Jun AU - van Rij, Jennifer AU - Yu, Yi-Hsiang AU - Li, Zhaobin AU - Bouscasse, Benjamin AU - Ducrozet, Guillaume AU - Bingham, Harry TI - Focused wave interactions with floating structures: a blind comparative study JF - PROCEEDINGS OF THE INSTITUTION OF CIVIL ENGINEERS-ENGINEERING AND COMPUTATIONAL MECHANICS J2 - P I CIVIL ENG-ENG COMPUT MECH VL - 174 PY - 2021 IS - 1 SP - 46 EP - 61 PG - 16 SN - 1755-0777 DO - 10.1680/jencm.20.00006 UR - https://m2.mtmt.hu/api/publication/32406784 ID - 32406784 AB - YThe 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 non-linear Navier-Stokes (NS) solvers, simulate the interaction between focused wave events and two separate, taut-moored, floating structures: a hemispherical-bottomed cylinder and a cylinder with a moonpool. The 'blind' numerical predictions for heave, surge, pitch and mooring load, are compared against physical measurements. Dynamic time warping is used to quantify the predictive capability of participating methods. In general, NS solvers and hybrid methods give more accurate predictions; however, heave amplitude is predicted reasonably well by all methods; and a WEC-Sim implementation, with CFD-informed viscous terms, demonstrates comparable predictive capability to even the stronger NS solvers. Large variations in the solutions are observed (even among similar methods), highlighting a need for standardisation in the numerical modelling of WSI problems. LA - English DB - MTMT ER - TY - JOUR AU - Davidson, Joshua Patrick AU - Henriques, Joao C. C. AU - Gomes, Rui P. F. AU - Galeazzi, Roberto TI - Opening the air-chamber of an oscillating water column spar buoy wave energy converter to avoid parametric resonance JF - IET RENEWABLE POWER GENERATION J2 - IET RENEW POWER GEN VL - 15 PY - 2021 IS - 14 SP - 3109 EP - 3125 PG - 17 SN - 1752-1416 DO - 10.1049/rpg2.12204 UR - https://m2.mtmt.hu/api/publication/32404421 ID - 32404421 AB - The oscillating-water-column (OWC) spar-buoy is a type of wave energy converter that may exhibit undesirable large roll and pitch amplitudes caused by a dynamic instability induced by parametric resonance. The occurrence of this phenomenon not only reduces the power extraction but significantly increases the structural loads on the buoy, the turbine rotor and on the mooring system. The paper compares the parametric resonance behaviour of two configurations of an OWC spar-buoy using experimental data obtained in a wave flume at a scale of 1:100. The configurations investigated were: (1) closed and (2) fully open-air chamber. The experimental tests covered a wide range of regular and irregular waves, as well as in free decay experiments. Results showed that opening the air chamber reduces the coupling between the buoy and the OWC within, thus shifting the damped natural heave frequency of the system in comparison with the closed chamber configuration. This effect changes parametric resonance characteristics of the two configurations due to the coupling between roll/pitch and heave modes. Moreover, for specific wave frequencies, the occurrence of parametric resonance observed when the chamber is closed do not occur while the air chamber is fully open. These results suggest the possibility of controlling a pressure relief valve installed on top of the device to reduce parametric resonance whenever this dynamic instability is detected. LA - English DB - MTMT ER - TY - JOUR AU - Windt, Christian AU - Davidson, Joshua Patrick AU - Ringwood, John V TI - Numerical analysis of the hydrodynamic scaling effects for the Wavestar wave energy converter JF - JOURNAL OF FLUIDS AND STRUCTURES J2 - J FLUID STRUCT VL - 105 PY - 2021 PG - 28 SN - 0889-9746 DO - 10.1016/j.jfluidstructs.2021.103328 UR - https://m2.mtmt.hu/api/publication/32404395 ID - 32404395 AB - Scaled model tests are an important step during the research and development of wave energy converters (WECs). While such scaled model tests in physical wave tanks are prone to undesired scaling effects due to e.g. mechanical artefacts and/or fluid effects, numerical wave tanks (NWTs) provide excellent tools for the analysis of WECs across a range of scales, overcoming the limitations of the physical test environment. Simultaneous scaling based on the Froude and Reynolds number is achievable in physical wave tanks only with significant effort, whereas NWTs allow the adjustment of fluid properties, such as viscosity, in an easy manner, thereby catering for Froude and Reynolds similarity. This study exploits the capabilities of a high-fidelity, computational fluid dynamics based, NWT and investigates the hydrodynamic scaling effects for the heaving buoy Wavestar WEC. Various test cases, relevant for WEC applications and with progressively increasing complexity, are considered to develop a comprehensive understanding of the scaling effects. Results show that significant scaling effects occur for the viscous component of the hydrodynamic loads on the WEC hull, while the system dynamics and total (viscous + pressure) loads are relatively unaffected by scaling effects. (C) 2021 The Author(s). Published by Elsevier Ltd. LA - English DB - MTMT ER - TY - JOUR AU - Kramer, Morten Bech AU - Andersen, Jacob AU - Thomas, Sarah AU - Bendixen, Flemming Buus AU - Bingham, Harry AU - Read, Robert AU - Holk, Nikolaj AU - Ransley, Edward AU - Brown, Scott AU - Yu, Yi-Hsiang AU - Tran, Thanh Toan AU - Davidson, Joshua Patrick AU - Horváth, Csaba AU - Janson, Carl-Erik AU - Nielsen, Kim AU - Eskilsson, Claes TI - Highly Accurate Experimental Heave Decay Tests with a Floating Sphere: A Public Benchmark Dataset for Model Validation of Fluid–Structure Interaction JF - ENERGIES J2 - ENERGIES VL - 14 PY - 2021 IS - 2 PG - 36 SN - 1996-1073 DO - 10.3390/en14020269 UR - https://m2.mtmt.hu/api/publication/31801208 ID - 31801208 N1 - Department of the Built Environment, Aalborg University (AAU), Thomas Mann Vej 23, Aalborg, 9220, Denmark Floating Power Plant (FPP), Park Allé 382, Vallensbæk, 2625, Denmark Sintex, Jyllandsvej 14, Hobro, 9500, Denmark Department of Mechanical Engineering, Technical University of Denmark (DTU), Nils Koppels Allé, Building 403, Kgs Lyngby, 2800, Denmark School of Engineering, Computing and Mathematics, University of Plymouth (UoP), Plymouth, Devon, PL4 8AA, United Kingdom National Renewable Energy Laboratory (NREL), 15013 Denver West Parkway, Golden, CO 80401, United States Department of Fluid Mechanics, Budapest University of Technology and Economics, Műegyetem rkp. 3, Budapest, 1111, Hungary Department of Mechanics and Maritime Sciences, Chalmers University of Technology (CTH), Gothenburg, 40482, Sweden Ramboll Group A/S, Hannemanns Allé 53, Copenhagen S, DK-2300, Denmark Research Institutes of Sweden (RISE), P.O. Box 857, Borås, SE-50115, Sweden Cited By :3 Export Date: 6 July 2022 Correspondence Address: Kramer, M.B.; Department of the Built Environment, Thomas Mann Vej 23, Denmark; email: mmk@build.aau.dk Funding details: U.S. Department of Energy, USDOE, DE-AC36-08GO28308 Funding details: Energistyrelsen, DEA Funding text 1: Funding: The work related to planning and analyzing the physical test results was funded by the Energy Technology Development and Demonstration Program (EUDP) under the Danish Energy Agency. NREL was funded by the U.S. Department of Energy under Contract DE-AC36-08GO28308. AB - Highly accurate and precise heave decay tests on a sphere with a diameter of 300 mm were completed in a meticulously designed test setup in the wave basin in the Ocean and Coastal Engineering Laboratory at Aalborg University, Denmark. The tests were dedicated to providing a rigorous benchmark dataset for numerical model validation. The sphere was ballasted to half submergence, thereby floating with the waterline at the equator when at rest in calm water. Heave decay tests were conducted, wherein the sphere was held stationary and dropped from three drop heights: a small drop height, which can be considered a linear case, a moderately nonlinear case, and a highly nonlinear case with a drop height from a position where the whole sphere was initially above the water. The precision of the heave decay time series was calculated from random and systematic standard uncertainties. At a 95% confidence level, uncertainties were found to be very low—on average only about 0.3% of the respective drop heights. Physical parameters of the test setup and associated uncertainties were quantified. A test case was formulated that closely represents the physical tests, enabling the reader to do his/her own numerical tests. The paper includes a comparison of the physical test results to the results from several independent numerical models based on linear potential flow, fully nonlinear potential flow, and the Reynolds-averaged Navier– Stokes (RANS) equations. A high correlation between physical and numerical test results is shown. The physical test results are very suitable for numerical model validation. LA - English DB - MTMT ER -