A summary of the Lucy Ashton resistance prediction workshop

A blind full-scale CFD resistance prediction workshop was held in 2024, with the Lucy Ashton paddle steamer as its test case. Results from forty participants were received for the three different parts in which the workshop was organised, which consisted of a grid refinement study with common grids, full-scale simulations for varying Froude number, and model-scale simulations at a constant Froude number for varying model sizes. This paper presents a summary of the results gathered for the workshop along with its main findings, and the comparison with the results available from the experimental campaign carried out for the Lucy Ashton in the 1950s. The computational results led to lower ship resistance than the experimental data for all conditions, due to the simula-tions considering the ship to be hydrodynamically smooth and to not heave or pitch. The scatter of the resistance at full-scale showed a decreasing trend as the Froude number was increased with a median absolute deviation of at most 2.3%. The spread in the numerical results obtained for the full-scale conditions was equivalent to that observed for the model-scale cases, building further confidence in full-scale CFD.