Drag generation mechanisms of artificial hairy biofilm-like surfaces

Hard and soft biofouling formation on naval objects has been shown to increase drag and cause performance deterioration. Understanding the drag generation mechanisms of soft biofouling is complicated due to the unconstrained nature of biofilm growth and the resulting non-uniform variations in the surface topologies among different trials. Studying hydrodynamic drag generation of biofilms in a laboratory setting is challenging due to inhomogeneities in geometry along the surface and sloughing during data collection. To isolate the effect of fouling geometry, the drag producing mechanism of artificial biofilm-like hairy surfaces is studied using a skin-friction flow test facility. Skin-friction coefficients of the compliant biofouling-like surfaces and their rigid replicas are estimated and compared. Interaction of the surfaces with the underlying flow is observed and compared using high-speed videos.