Scour mitigation measures around offshore wind structures using experimental models.

Motivated by the expansion of the offshore wind industry, research on scour around subsurface structures has gained momentum in recent years. This study focuses on flow-altering scour mitigation methods which would be suitable for use within the offshore environment. This research project incorporates the design and execution of a numerical study alongside extensive experimental investigations. These investigations aim to explore scour processes and identify effective mitigation strategies for offshore structures.Following a comprehensive review of existing scour mitigation methods, the research focused on exploring alternatives to traditional rock armour, this objective guided the formulation of research aims for this thesis. The study incorporated a fundamental understanding of scour processes, specifically the effect of structure-induced flow patterns on the downflow, horseshoe vortex, and lee-wake vortices. Numerous alternative mitigation methods were evaluated in a controlled experimental model to assess their effectiveness in mitigating scour. These methods included collars of varying diameters positioned at different elevations relative to the bed, collars incorporating textured vegetation, rock bags, and textured piles. A novel data collection technique utilising an acoustically transparent Mylar Film was implemented to facilitate continual monitoring of bed changes beneath the collars. The experimental investigations were conducted in a laboratory setting under various flow regimes, including unidirectional clear water and live bed flows, as well as additional tests simulating bi-directional currents.This research yielded a multitude of original results and established a novel data collection method using Mylar Film for continuous under-collar monitoring. The findings presented in this thesis demonstrate that the use of collars at optimal heights and diameters with and without added texture offers viable alternatives to traditional rock armour for scour mitigation. This work will contribute to the advancement of scour mitigation methods and experimental model investigations.