Numerical investigation of added resistance of a container ship in short regular waves using unsteady RANS simulations

Accurately predicting the added resistance coefficient in short waves remains a challenge. This study aims to investigate the added resistance of a container ship in regular short-head waves at moderate Froude numbers through unsteady RANS simulations. A body-fitted, full-hexahedral unstructured mesh models the ship’s motion, while the volume of fluid (VoF) method determines the free surface. Regular head waves of relatively short wavelengths, ranging from 0.22 ≤ λ/LPP ≤ 0.65, are considered in the simulations. The study first examines the stability of the generated waves, followed by an analysis of the wave field around the hull with the ship present, and an assessment of the numerical residual. Fast Fourier Transform (FFT) is applied to the non-dimensional longitudinal force in regular head waves to calculate the mean value of the added resistance. This is to remove the noise in the force signal. Detailed analyses of flow characteristics, including free-surface elevation and pressure distribution, are performed. Pressure distribution contours visually identify hull regions contributing significantly to the added resistance. Simulation results are compared to available experimental data and results based on empirical methods recommended by authorities. This study aims to establish a practical procedure for obtaining reliable added resistance coefficient in short waves.