Numerical investigation of skin friction drag due to marine biofouling by barnacle aggregations*

Skin-friction drag is the dominant component of drag for most sea-faring vessels. With the accumulation of marine organisms on ship hulls, skin-friction drag increases dramatically, increasing fuel consumption and associated emissions such as CO₂, NO_x and SO_x. Barnacles are one of the most common type of marine organisms found on fouled ship hulls, and they are also considered one of the most difficult to deal with. In this work, the fluid dynamic properties of surfaces partially populated with representative barnacle colonies are investigated using direct numerical simulations at a range of friction Reynolds numbers. With this method integral quantities such as the Hama roughness function ΔU⁺ and the equivalent sand grain roughness k_s can be evaluated, while turbulence statistics sampled between and directly above the barnacles can provide insight about the effects this type of marine biofouling induces into the near-wall flow.