Session: 09-02-02 Wave Energy: Hydrodynamics 2

Paper Number: 125065

125065 - Influence of Underlying Currents on the Performance of a Taut-Moored Point-Absorber Wec: An Investigation via High-End Numerical Tools 

To finally breakthrough as a reliable and cost-effective source of green energy, wave energy converters (WECs) should guarantee efficient power generation and low risk factors under a broad variety of load conditions. Marine environmental loads have been extensively categorized and applied to offshore structures as a series of different components, such as wave-, current-, or wind-related actions. However, the physical combination of such phenomena may hold sway on the structure’s response more than the afterthought addition of loading factors. This may easily take form into the case of waves and current combinations, substantially affecting the wave characteristics as well as the flow velocity field. Experimental campaigns investigating such multifaceted environmental conditions, however, require considerable resources and dedicated infrastructures which necessarily increase the cost of the design process. High-end numerical models represent a viable alternative into the investigation of the effects of combined loading on floating moored structures [1]. In the first instance, they can examine how accurately the flow description reflects their hydrodynamic behavior, and subsequently, assess how this modification may impact their survivability and efficiency.

Therefore, a numerical campaign on a taut-moored point-absorber WEC is conducted here, with the aim of providing useful insights into the modified power absorption and operational or extreme load conditions, when the flow field features the coexistence of waves and current. The WEC model tested is the Uppsala University WEC (UUWEC), which has been validated in several numerical frameworks and conditions. Among the latter, the Smoothed Particles Hydrodynamics-based (SPH) DualSPHysics [2] solver has delivered excellent performance in simulating the UUWEC [3], and moving floating structures in general [4], as it overcomes the traditional limitations of mesh-based methods when facing harsh marine environments. Within this SPH framework, augmented with external libraries to include mechanical and structural features relative to WECs systems, such as the mooring lines or the Power Take-Off (PTO) system, a numerical wave-current flume is implemented and utilized to investigate the response of the UUWEC under a range of wave-current combinations. The results show that direction and intensity of the current may affect the power absorption and anchoring tension average and peaks trend, also considering the nonlinearity induced by the presence of the PTO unit. Careful examination of these adjustments can yield enhanced performance of point-absorber devices. Flexible design strategies and active control systems may be implemented to anticipate and address complex marine environments characterized by multiple sources of pressures.

[1] Capasso, S. et al. “Numerical Simulation of a Moored Wave-Buoy in Waves and Current by Smoothed Particle Hydrodynamics.” Volume 7: CFD & FSI. American Society of Mechanical Engineers (2023).

[2] Domínguez, J. M. et al. “DualSPHysics: From Fluid Dynamics to Multiphysics Problems.” Computational Particle Mechanics 9.5 (2022): 867–895.

[3] Tagliafierro, B. et al. “A Numerical Study of a Taut-Moored Point-Absorber Wave Energy Converter with a Linear Power Take-Off System Under Extreme Wave Conditions.” Applied energy 311 (2022).

[4] Crespo, AJC. et al. “On the state-of-the-art of CFD simulations for WECs within the open-source numerical framework of DualSPHysics.” Proceedings of the 15th European Wave and Tidal Energy Conference, Bilbao, Spain (2023).

Presenting Author: Salvatore Capasso Università degli Studi di Salerno

Presenting Author Biography: I am a Civil Engineer and Architect, graduated at the University of Salerno. I am currently involved in the PhD Program of the Civil Engineering Department at University of Salerno, investigating Fluid-Structure Interaction using an high-fidelity CFD open-source code, DualSPHysics, based on the Smoothed Particle Hydrodynamics technique. As part of the collective DualSPHysics solver project, I am actively collaborating to extend the applicability of the code to various field of Civil engineering, including flexible structures and realistic environmental conditions for offshore structures for renewable energy harvesting.

Authors:

Salvatore Capasso Università degli Studi di Salerno
Bonaventura Tagliafierro Universitat Politècnica de Catalunya
Malin Göteman Uppsala Universitet
Iván Martínez-Estévez Universidade de Vigo
José Manuel Domínguez Universidade de Vigo
Corrado Altomare Universitat Politècnica de Catalunya
Moncho Gómez-Gesteira Universidade de Vigo
Alejandro j.c. Crespo Universidade de Vigo
Giacomo Viccione Università degli Studi di Salerno