Effects of Homogeneous Hull Surface Roughness on the Ship Friction Resistance

Biofouling stuck on the ship hull increases the surface roughness of the hull, resulting in an increased ship resistance and leading to increased ship fuel consumption with the associated air pollution. Effects of homogeneous hull surface roughness on the ship friction resistance are investigated in this study by utilizing a computational fluid dynamics method. Four surface conditions are considered, namely, a smooth surface and three rough surfaces, denoted as P, Q, and R, with equivalent sand-grain roughness height ks = 125, 269, and 425 μm, respectively. Simulation results show that the friction-resistance coefficient CF increases with increasing ks for the same Reynolds number Re. For the smooth surface case, CF decreases with increasing Re, but it increases with increasing Re for the rough surface case. For the mild-biofouling case considered in this study, the increase of CF reaches 57.08% at Re = 2.16 × 109 and 63.36% at Re = 2.73 × 109.