EXPERIMENTAL WAKE DYNAMICS OF PILES WITH ARTIFICIAL BIOFOULING IN WAVES

Offshore structures become colonized by marine orga-nisms after a short period of time, whose common benthic communities depend among others on geographic location, water depth, water temperature, food supply, salinity and oxygen content of the water (Kröncke and Bergfeld, 2003; Shi et al., 2012). While biofouling can be categorized in biological terms as bivalves, kelp, algae, barnacles, tubeworms and other species (van der Stap et al., 2016; Wilhelmsson and Malm, 2008), engineers mostly distinguish between hard and soft marine growth based on the strength of their outer shell alone (Shi et al., 2012; Skaugset and Baarholm, 2008). Due to an increasing demand for sustainable energy, the offshore renewables industry experiences significant growth. However, many uncertainties persist in the consideration of biofouling, specifically when calculating loads accor-ding to the Morison concept, the influence of marine fouling on fatigue reassessment, on the flow velocities around cylinders and the vortex formation under waves. For the first time, the flow around cylinders with different artificial marine biofouling was recorded and analyzed in an extensive experimental study using a comprehensive 4D particle tracking velocimetry (PTV) system.