Numerical simulation of ships navigating through broken ice fields.

This study investigated the effects of different bow shapes on channel resistance. In this paper, specifically examined angles: the waterline entrance angle (alpha), the stem angle at the centerline (phi 1), and the stem angle at the waterline at breadth B/4 (phi 2). 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 alpha, phi 1, and phi 2.
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, phi 1 is not incorporated in the FSICR resistance equation. Therefore, effects of phi 1 cannot be observed in FSICR. Simulation results show that the resistance decreases as phi 1 increases. As phi 2 increases, channel resistance also increases. The FSICR resistance formula shows this trend irrespective of alpha. However, our calculation results show that as alpha decreases, the effect of phi 2 also decreases. For FSICR, the channel resistance does not change markedly when alpha is changed from 15 degrees to 25 degrees. It sometimes decreases. When alpha is increased from 25 degrees, the resistance increases unconditionally in all cases. In this simulation, the resistance increases constantly when alpha increases.

本研究探讨了不同船首形状对航道阻力的影响。本文具体考察了三个角度：水线入口角（α）、中线处的艏柱角（φ₁）以及船宽B/4处水线位置的艏柱角（φ₂）。通过组合这些角度，生成了多种具有不同船首形状的船舶模型。利用这些模型，我们对碎冰航道的阻力进行了数值评估，并将结果与芬兰-瑞典冰级规则（FSICR）中的航道阻力进行了对比。此外，我们还探讨了α、φ₁和φ₂变化时阻力的变化趋势。结果表明，本研究模拟得到的阻力最小仅为FSICR中阻力的1/4。然而，模拟结果与FSICR中的计算值之间存在线性相关性，且二者具有定性一致性。在计算无固结层碎冰航道的阻力时，FSICR阻力方程未纳入φ₁，因此无法在FSICR中观察到φ₁的影响。模拟结果显示，阻力随φ₁增大而减小；随φ₂增大而增大。FSICR阻力公式显示，无论α取值如何，这一趋势均成立。但本研究计算结果表明，随着α减小，φ₂的影响也会减弱。对于FSICR而言，当α从15度变为25度时，航道阻力无显著变化，有时甚至会减小；而当α从25度开始增大时，阻力在所有情况下均无条件增加。本模拟中，阻力随α增大而持续上升。