Numerical investigation on the effect of homogenous roughness due to biofouling on ship friction resistance

Ships are subject to increased surface roughness due to the attachment of biofoulings on their hull. When the surface of a ship's hull is rough, increased frictional resistance can be expected. A ship's frictional resistance make up almost 80 - 85% of its total resistance. Therefore, it is crucial to maintain the ship's frictional resistance value to a minimum. In this study, the effects of roughness length scale due to biofouling on friction resistance are investigated. To achieve reliable results, this study used the 3D DTMB 5415 model that was established as a benchmark study by ITTC. Roughness length scales representing biofoulings are applied to the model and analyzed by using the CFD software at a service speed, reaching a Froude Number of 0.28. Results of the simulation are compared and analysed to gain an understanding of the increased friction resistance value due to biofouling. For the smooth case, the results are in agreement with the towing test conducted by ITTC. In addition, friction resistance is found to be increasing along with the rise of the roughness length scale.