HYDRODYNAMIC EFFECTS OF SURFACE ROUGHNESS ON CYLINDERS: LITERATURE REVIEW AND RESEARCH GAPS

In recent years, several studies have been performed to assess the damages caused by marine biofouling. Marine biofouling (or marine growth) generally refers to the settlement and growth of unwanted aquatic organisms on human-made structures situated in marine and estuarine environments. Regarding the continued demonstration of energy resource potential and a promising area of research by offshore wind turbines (OWTs), this paper provides a review of biofouling phenomena in the context of underwater cylindrical components of offshore/marine structures. Most floating wind turbine installations are located in moderate water depths between 50 m to 100 m. At these depths, biofouling can be seen on a large section of cylindrical structures, including mooring lines or power cables, with considerable roughness. The proposed review will specifically highlight various marine fouling parameters and laboratory approaches employed by researchers in modelling biofouling, and its effects on hydrodynamic loading due to wave and current excitation. Most previous experimental research assumed that biofouling effects are a function of surface roughness that is either uniform or nearly uniform and that the stationary roughened cylinder is fully covered. Some other studies, however, have proven that the surface roughness alone cannot precisely characterize marine growth; other marine fouling parameters such as roughness geometry, surface coverage ratio, facility testing set-up, biofouling species, and colonization pattern can all have a significant impact on the hydrodynamic force coefficients. To highlight knowledge gaps and research trends on collective influential aspects of biofouling to date. This report went on to explore the challenges in modelling biofouling due to its intrinsic randomness and uncertainty, as well as suggestions for many studies on marine fouling that are currently absent.