P2.20 Thursday, Jan. 5 Flow-generated forces on hull fouling organisms and relationship to hydrodynamic self-cleaning of fouling-release coatings HOLM, E.R.*; GOWING, S.; SANCHEZ DE LOZADA, M.F.; Naval Surface Warfare Center, Carderock Division; Naval Surface Warfare Center, Carderock Division; Naval Surface Warfare Center, Carderock Division email@example.com
Fouling-release coatings represent a non-toxic approach to the control of ship hull fouling. These coatings allow organisms to attach but promote their release from the hull as a result of hydrodynamic forces experienced during routine operations (hydrodynamic self-cleaning). More complete knowledge of the hydrodynamic forces experienced by fouling organisms improves our ability to predict the efficacy of fouling-release coatings. As well, the data can produce performance targets for polymer chemists or materials developers. We are using an experimental approach to quantify the forces generated by ship movement on organisms recognized as important ship hull foulers. Initial experiments focus on three types of sessile invertebrates; barnacles, serpulid tubeworms and bivalve mollusks. Organisms are scanned with a laser, resulting in three-dimensional point clouds that are processed into CAD models for manufacture by Rapid Prototyping. Hydrodynamic testing is performed in a 30.5 cm water tunnel on models scaled for accurate force measurement. Model organisms are rotated to allow measurement of three orthogonal forces at all angles to the direction of flow. Screens are used to vary the boundary layer thickness to simulate the effect of location of the fouling organism along the ship hull. Our approach and results may also be applicable to sessile invertebrates occurring in wave-swept or other hydrodynamically-challenging environments.