Citation: Trivedi, K.; Ray, A.R.; Krishnan, P.A.; Koley, S.; Sahoo, T. Hydrodynamics of an OWC Device in Irregular Incident Waves Using RANS Model. Fluids 2023, 8, 27. https://doi.org/10.3390/ fluids8010027 Academic Editors: Mehrdad Massoudi and Rajinder Pal Received: 25 October 2022 Revised: 13 December 2022 Accepted: 27 December 2022 Published: 11 January 2023 Copyright: © 2023 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/). fluids Article Hydrodynamics of an OWC Device in Irregular Incident Waves Using RANS Model Kshma Trivedi 1 , Amya Ranjan Ray 1 , Parothidil Anjusree Krishnan 1 , Santanu Koley 1, * and Trilochan Sahoo 2 1 Department of Mathematics, Birla Institute of Technology and Science—Pilani, Hyderabad Campus, Hyderabad 500078, India 2 Department of Ocean Engineering and Naval Architecture, Indian Institute of Technology Kharagpur, Kharagpur 721302, India * Correspondence: santanukoley1989@gmail.com or santanu@hyderabad.bits-pilani.ac.in; Tel.: +91-040-6630-3588 Abstract: This research examines the hydrodynamic performance of an oscillating water column device placed over a sloping seabed under the influence of irregular incident waves. The numerical model is based on the Reynolds-veraged Navier–Stokes (RANS) equations with a modified k − ω turbulence model and uses the volume-of-fluid (VOF) approach to monitor the air–water interface. To explore the hydrodynamic performance of the OWC device in actual ocean conditions, the Pierson– Moskowitz (P-M) spectrum was used as the incident wave spectrum, together with the four distinct sea states which occur most often along the western coast of Portugal. The numerical simulation offers a comprehensive velocity vector and streamline profiles inside the OWC device’s chamber during an entire cycle of pressure fluctuation. In addition, the impact of the irregular wave conditions on the free-surface elevation at various places, the pressure drop between the chamber and the outside, and the airflow rate via the orifice per unit width of the OWC device are investigated in detail. The results demonstrate that the amplitudes of the inward and outward velocities via the orifice, free-surface elevations, and flow characteristics are greater for more significant wave heights. Further, it is noticed that the power generation and capture efficiency are higher for a seabed having moderate slopes. Keywords: water waves; oscillating water column device; irregular waves; RANS-VOF; ANSYS- Fluent 1. Introduction Socioeconomic development has accelerated, and energy, particularly crude oil, plays a unique role in the expansion and growth of the global economy [1]. This world-renowned expansion, however, has been accomplished at the expense of natural resources and the environment. Moreover, the depletion of non-renewable energy sources, population growth, climate change, and global warming challenges have placed governments in a precarious position regarding the promotion of renewable energy [2]. Renewable energy is garnering more attention and is widely recognized as the greatest solution to the growing cost of fossil fuels and imminent survival issues. In a bid to save the environment from the harmful consequences of fossil fuel emissions, the use of renewable energy sources over the long run is cost-effective [3]. Due to the high energy-density flux of ocean waves relative to other renewables, such as solar and wind, and their lower contribution to environmental contaminants and global warming, the energy linked with ocean waves is of considerable importance to researchers today [4]. In order to convert wave energy into electricity, several wave-power production prototypes have been designed and deployed across the globe. However, the oscillating water column (OWC) wave energy converter device is more popular, owing to its feasibility and simple operating mechanism. The OWC device Fluids 2023, 8, 27. https://doi.org/10.3390/fluids8010027 https://www.mdpi.com/journal/fluids