Viscoelasticity and Associated-drag of Artificial and Natural Marine Fouling Biofilms

Biofilm associated drag on a marine vessel is estimated to be between 1-18% (Schultz at al., 2011). Current equipment used to estimate biofilm-associated drag (ex. MATRIX flume at AkzoNobel), has been calibrated using different sandpapers, which are rigid structures of defined and homogenous roughness and are not deformed by fluid flow. Biofilm roughness can be measured. However, biofilms are viscoelastic materials and so deform under shear flow, producing a multitude of biofilm-fluid interactions that subsequently influence drag. As such, rigid roughness calibrations do not directly translate to biofilm drag for equivalently rough biofilms. This project encompasses the development of novel synthetic biofilms from compliant materials and measuring physicomechanical properties of biofilms (both artificial and natural), particularly viscoelasticity, for calibrating marine biofilm drag to that of compliant materials. In the longer term the data, methods, and knowledge generated from this project will support the development of coatings with properties tailored to reduce drag penalties from marine biofilm fouling.