Resistance Evaluation of Ship Navigation in Brash Ice Channels with Physically Based Modeling
Resistance Evaluation of Ship Navigation in Brash Ice Channels with Physically Based Modeling
复制标题
DOI：
--
复制
发表时间：
2009
期刊：
影响因子：
--
通讯作者：
A. Konno
中科院分区：
文献类型：
--
作者：
A. Konno
芬兰-瑞典的冰级规则（FSICR）要求对每艘船在浮冰通道中的阻力进行估计，以获得冰级认证，并且“基于更精确的计算或基于模型试验的值”的阻力评估可能得到批准。为了提供一种更精确的计算方法，本文提出了一种计算船舶在浮冰航道中阻力的数值模拟方法。该模拟器使用基于物理的建模。本文介绍了用仿真器在模型尺度上估计通道电阻，用三次律在实际尺度上估计通道电阻。在模拟中，一艘船被拖曳在一个充满小球形和立方冰块的通道中。船和冰块被建模为刚体；一个虚拟的流体力作用在每一块冰块上，以重现船周围的流体效应。还考虑了静压下的浮力。恢复系数设为零，冰片间摩擦系数设为1.35，根据相关文献的描述。测试了两种类型的船首，五种航道长度和两种尺寸的冰块。数值模拟结果表明，该模拟器能够模拟浮冰通道中浮冰块的运动，并能在一定条件下对浮冰通道中的船舶阻力进行评估。从模拟中估计的通道电阻与FSICR规则公式具有相同的数量级，但是FSICR规则公式的两倍，这表明模拟器高估了通道电阻。讨论了尺寸分布和摩擦系数的影响。
Finnish–Swedish ice class rules (FSICR) require estimation of a ship’s resistance in brash ice channels for each ship to obtain certification of an ice class, and evaluation of resistance “based on more exact calculations or values based on model tests might be approved.” The authors have developed a numerical simulation method to evaluate ship resistance in brash ice channels to provide a more exact calculation method. This simulator uses physically based modeling. This paper presents evaluation of channel resistance on a model scale using the simulator, and estimation of the resistance on a real scale using the cubic law. For the simulation, a ship is towed in a channel filled with small spherical and cubic ice pieces. The ship and ice pieces are modeled as rigid bodies; a virtual fluid force acts on each ice piece to reproduce the fluid effect around the ship. Buoyancy with static pressure is also considered. The coefficient of restitution is set to zero and the friction coefficient between ice pieces is set to 1.35, as given from descriptions in the related literature. Ship bows of two types, five channel lengths and two sizes of ice pieces are tested. Results of numerical simulations show that the authors simulator can simulate motions of ice pieces and can evaluate ship resistances in brash ice channels under certain conditions. Channel resistances estimated from the simulations are of the same order of magnitude as that of FSICR rule formula, but twice as much as that, which suggests that the simulator overestimates channel resistance. Effects of size distribution and friction coefficient are discussed.