An investigation into the effect of hard fouling on the ship resistance using CFD

Biofouling is the colonization of underwater surfaces by microorganisms, plants, algae or animals and can be divided into soft and hard fouling. Soft fouling is consisted of algae, slime and grasses and typically has a lower impact on the performance of the ship than hard fouling, which has a calcareous structure. Furthermore, hard fouling can be extremely detrimental to the performance of machinery and coating systems. Within this paper, the effect of hard fouling on the ship resistance is assessed utilizing Computational Fluid Dynamics (CFD). The roughness function model for the hard fouling is implemented within the wall function of the CFD software. Afterwards, numerical simulations of fouled flat plates are performed, and the obtained results are verified and validated with the experimental results published in the literature. Once validated, numerical simulations with implemented roughness function model and roughness length scale, proposed in the literature, can be used for the determination of the effect of hard fouling on the resistance of any arbitrary body. Lastly, the effects of hard fouling on the resistance characteristics of two merchant ships at full-scale are determined utilizing the validated CFD model. Benefits of the proposed method for the determination of the effect of hard fouling on the ship resistance are highlighted and discussed.