Journal of Ocean Engineering and Technology (한국해양공학회지)

Korean Society of Ocean Engineers (한국해양공학회)
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Effects of Irregular Bathymetry on the Performance and Wake Characteristics of Tidal Stream Turbines: A Case Study of a Tidal Power Site

  • Ngome Mwero (Graduate School of Integrated Science and Technology, Nagasaki University) ;
  • Song Fu (Department of Mechanical and Aerospace Engineering, University of Strathclyde) ;
  • Takafumi Inamitsu (Graduate School of Integrated Science and Technology, Nagasaki University) ;
  • Stephanie Ordonez-Sanchez (Department of Mechanical and Aerospace Engineering, University of Strathclyde) ;
  • Benson Mwangi (Department of Marine Engineering, Jomo Kenyatta University of Agriculture and Technology) ;
  • Patxi Garcia-Novo (Institute of Integrated Science and Technology, Nagasaki University) ;
  • Cameron Johnstone (Department of Mechanical and Aerospace Engineering, University of Strathclyde) ;
  • Daisaku Sakaguchi (Institute of Integrated Science and Technology, Nagasaki University)
  • Received : 2024.11.14
  • Accepted : 2025.02.03
  • Published : 2025.02.28
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Abstract

Tidal energy has emerged as a promising renewable energy source, with abundant marine resources available in many parts of the world. To exploit this resource efficiently, reliable and computationally efficient methods are required to analyze energy yields from tidal arrays in real sites worldwide. This paper investigates the impact of irregular-bathymetry seabed elements near a tidal turbine location on the turbine's performance and wake. A high-resolution three-dimensional bathymetry model was created, and full-scale unsteady simulations were performed using the ANSYS-Fluent computational fluid dynamics tool and the Shear Stress Turbulence (SST) model for two cases: one with the site bathymetry and one with a flat seabed. Compared to the flatbed case, the results show a 1.84% increase in the average turbine power output for the site-bathymetry case. A 4.1% increase in average wake recovery rate was observed near the hill-like seabed features from 3D to 7D downstream from the turbine, followed by 11% reduction in wake recovery rate over the bathymetry slope from 9D downstream from the turbine. The findings of this study highlight the implications of bathymetry-generated effects in optimal site selection and tidal energy farm design.

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Acknowledgement

This work was supported by a Grant-in-Aid for Early-Career Scientists (24K17456) from the Japan Society for the Promotion of Science, and by the Royal Society of Edinburgh 2023 Scottish Government SAPHIRE Grant award (ID: 3959).