Ship bow shape effects on brash ice channel resistance

Abstract

This study investigated the effects of different bow shapes on channel resistance. In this paper, specifically examined angles: the waterline entrance angle (α), the stem angle at the centerline (φ1), and the stem angle at the waterline at breadth B/4 (φ2). Several ship models with different bow shapes were generated by combining these angles. Using these models, we evaluated the resistance of the brash ice channel numerically. Results were compared to channel resistance in the Finnish–Swedish Ice Class Rules (FSICR). Additionally, we investigated trends of resistance for varied α, φ1, and φ2.Results show that the resistance obtained in our simulation was as small as 1/4 of the resistance in FSICR. However, linear correlation was found between our simulation results and the calculations in FSICR. Our simulations show qualitative agreement. When calculating channel resistance for brash ice without consolidated layers, φ1 is not incorporated in the FSICR resistance equation. Therefore, effects of φ1 cannot be observed in FSICR. Simulation results show that the resistance decreases as φ1 increases. As φ2 increases, channel resistance also increases. The FSICR resistance formula shows this trend irrespective of α. However, our calculation results show that as α decreases, the effect of φ2 also decreases. For FSICR, the channel resistance does not change markedly when α is changed from 15 degrees to 25 degrees. It sometimes decreases. When α is increased from 25 degrees, the resistance increases unconditionally in all cases. In this simulation, the resistance increases constantly when α increases.