Fluid dynamics inside a U-shaped oscillating water column (OWC): 1D vs. 2D CFD model

Several mathematical models have been proposed in the last decades, focusing on peculiar aspects of dynamic behaviors of OWCs Wave Energy Converters (WEC). Computational fluid dynamics (CFD) studies have been widely diffused in the recent past, thanks to the strong increasing of computing power. Numerical wave flumes, both 2D or 3D, are become refined tools of investigations. However, there are tasks performed effectively and conveniently through 1D mathematical models, which require much less time of setup and running, in respect to CFD. Tuning the eigenperiod of a plant with most energetic waves is the most important of these tasks. It requires several trials, changing the size of some geometric parts of the device. In this work, we improved a conventional 1D mathematical model, by removing the assumption of polytropic transformation of the air mass inside the plenum, which is physically not consistent, and considering the actual asymmetry of thermodynamics during inhalation and exhalation phases. The results were validated through a numerical experiment carried out in a 2D numerical wave flume, considering a U-OWC at a full scale, achieving an excellent agreement of pressure and temperature variations in the plenum chamber. (C) 2022 Published by Elsevier Ltd.