Full-scale CFD simulations for the determination of ship resistance as a rational, alternative method to towing tank experiments

Results of ship resistance predictions obtained from towing tank experiments are affected by the method used to extrapolate from a model scale to a ship scale. Selection of method to determine a form factor is subjective and the extrapolation method is accurate for typical hull forms. For innovative hull forms the proper method for calculating the form factor is questionable. Moreover, the influence of the extrapolation method can be equally as important as the influence of a redesigned hull form itself. The paper presents novel numerical and experimental methods used to predict ship's total resistance in calm water. The results determined by towing tank experiments, full-scale CFD simulations and ship's sea trial measurements were compared. Depending on the method used, the determined form factor differed by 19%. As a result, the predicted calm water resistance varied from -6% to 11% relatively to sea trials data. For innovative hull forms in particular, full-scale CFD simulations should support the towing tank method. The results calculated by full-scale CFD varied from -10% to 4% relatively to sea trials data depending on the assumptions on hull roughness and turbulence model. The towing tank testing and full-scale CFD simulations can provide similar accuracy.