Prediction and empirical formula correction for brash ice resistance using CFD-DEM based on invisible bulbous bow ship

With the development of polar shipping, invisible bulbous bows are increasingly utilized in the design of polar transport vessels. However, there is a paucity of literature addressing their performance in ice conditions. To bridge this gap, this paper establishes a Computational Fluid Dynamics method combined with the Discrete Element Method (CFD-DEM) model to simulate ship-ice-fluid interaction for ships with invisible bulbous bows. The accuracy of the CFD-DEM model is validated through a model test conducted at the Hamburg Ship Model Basin. Furthermore, recognizing the significant errors in predicting ice resistance for this ship type using traditional formulas, this paper proposes a correction to the Riska formula for predicting brash ice resistance in ships with invisible bulbous bows. Based on data from CFD-DEM numerical calculations, an exponential correction and coefficient adjustment method is employed to modify the Riska brash ice resistance formula. The corrected empirical formula aligns closely with the numerical results. To further validate the feasibility of the corrected formula, ice resistance forecasts for two additional ships with invisible bulbous bows were performed using both the original and corrected Riska formulas. The results demonstrate that the original formula's calculations significantly deviate from actual values, whereas the corrected formula closely aligns with actual values, affirming the reliability of the correction. This study provides valuable reference material for researchers studying the brash ice performance of ships with invisible bulbous bows and for those revising brash ice resistance formulas.