Numerical Study of Effects of Inhomogeneous Roughness on the Ship Friction Resistance

Department of Naval Architecture, Sepuluh Nopember Institute of Technology (ITS), 60111 Surabaya, Indonesia

^* Corresponding author: k_suastika@na.its.ac.id

Abstract

The cleanliness of a ship hull is crucial for energy saving. Biofouling, which can cause microbiological corrosion, can also increase ship resistance. If left unchecked, this can lead to inefficient energy use and increased emissions, contributing to global warming. Ship resistance is a critical factor in ship design, which affects ship powering. The analysis of friction resistance due to biofouling on a ship hull requires an examination of the distribution of roughness height (k_s), which is randomly distributed. In this study, an analysis of friction resistance coefficient (C_F) due to inhomogeneous roughness is carried out with the help of CFD simulations with a full-scale model at 19 kn and 24 kn. The roughness of three ship segments, namely aft-hull, midship, and fore-hull, varies with ks values of 125 μm (P), 269 μm (Q), and 425 μm (R), respectively, while maintaining the same wetted surface area (S) in each segment. According to the simulation results, the RQP model produces the highest C_F of 2.154 x 10^-3, while the PQR model produces the smallest C_F of 2.119 x 10^-3 each at speed 24 knots. The C_F contributes an average of 72.2% CT.