The NW European shelf seas are attracting the rapidly developing offshore wind industry, which has the potential to provide large-scale electricity production from renewable sources. The installation of monopile infrastructure in shelf seas can induce turbulent wakes in regions characterised by strong currents – that can enhance localised mixing rates and drive changes to sediment dynamics, water quality, and ecosystem functioning. Ocean monitoring and modelling provide an opportunity to characterise the turbulent wakes and environmental feedbacks. This study focuses on resolving individual monopile wake profiles from an installed offshore wind turbine (North Wales, UK), by employing field observations and hydrodynamic modelling. High-resolution (monopile-scale) simulations were conducted using both depth-averaged and 3D, unstructured grid, hydrodynamic models (TELEMAC). The simulations were validated against local tide gauge data and Acoustic Doppler Current Profiler deployments in the monopile wake region. Subsequent simulations indicated that the turbulent wake extends 50 - 100 m downstream from the structure, varying with the spring–neap tidal regime. A deficit in the mean velocity of up to 30% was observed within the wake core, with stronger reductions during peak flood tides compared with ebb tides. Comparison between 2D and 3D models revealed that 2D depth-averaged simulations underestimated wake intensity due to the absence of vertical shear effects, whereas the 3D model captured more pronounced wake asymmetry and enhanced turbulence production. These findings provide insights into wake-induced hydrodynamic modifications in shelf seas and highlight the importance of resolving 3D turbulence dynamics for accurate environmental impact assessments in offshore wind farm planning. As offshore wind farms expand into deeper waters, understanding wake behaviour in stronger and more variable currents becomes essential, particularly for assessing cumulative wake effects, optimising turbine spacing and evaluating broader hydrodynamic impacts at larger spatial scales.
Hydrodynamics of Turbulent Wakes of Offshore Windfarm Monopile Foundations
Taran, O. (Author). 4 Jun 2025
Student thesis: Masters by Research