Assessment of the effect of speed and scale on the total resistance and its components for a bulk carrier

Reducing greenhouse gas emissions has become one of the primary goals for maritime transport today. One widely adopted, short-term, and cost-effective operational measure is slow steaming. Therefore, it is essential to assess the resistance characteristics of ships operating at reduced speeds, given that each vessel is optimized for a specific design speed. Computational fluid dynamics is employed to predict the total resistance coefficient and its components and to determine the form factor at various speeds and scales. The numerical approach is based on the Reynolds Averaged Navier-Stokes equations, discretized using the finite volume method. The study employs two numerical approaches: simulations conducted both with and without the presence of the free surface. This allows the decomposition of the total resistance coefficient into its components, namely, frictional, viscous pressure, and wave resistance coefficients. The results show significant scale effects and a minor effect of speed on the total resistance coefficient and its components. The total resistance coefficient and its components decrease as speed increases and scale decreases. The virtual fluid method is employed, and the results show that the total resistance coefficient and its components for the full-scale ship can be derived from numerical simulations conducted at model scale. Although speed has a minor effect on the form factor, significant scale effects are observed.