Evaluating Hydrodynamic Influences on Ice Load from Ship-Ice Glancing Impact: The Roles of Sea Waves and Hydrodynamic Interactions

With climate change increasing accessibility to polar maritime routes, understanding ice loads on ship hull has become crucial for safe navigation. Traditional methods for evaluating ice loads, such as the Popov method, often simplify the geometry of ships and ice floes, and neglect the complex hydrodynamic interactions and waves that significantly influence ice loads. These simplifications can lead to inaccurate predictions of ice loads, especially in the Marginal Ice Zone (MIZ), where ships and small to medium-sized ice floes are dynamically affected by sea waves. This research aims to fill this gap by developing a comprehensive model that incorporates these factors to enhance the precision of energy-based ice load evaluations. To address these shortcomings, this research proposes a novel approach using the Boundary Element Method (BEM) to assess the hydrodynamic interaction between an advancing ship and an ice floe. This approach incorporates the linear superposition principle to combine the radiation potentials of both bodies and the encounter frequency method to account for the ship's speed. This results in a detailed calculation of added mass and damping coefficients, which are critical for understanding the hydrodynamic interactions between the ship and ice. Further, a Computational Fluid Dynamics (CFD) model is developed to investigate the hydrodynamic coefficients under the interaction between side-by-side structures, focusing on how the surrounding fluid flows affect the hydrodynamic coefficients. The CFD model helps understand the physical significance of specific subsections of the hydrodynamic coefficient matrix, essential for accurate ice load evaluations. The research integrates these findings into an extended energy-based model for ice load evaluation, considering effects of waves and hydrodynamic interactions. This model is illustrated through a case study involving an ice-class ship and ice floes of varying sizes. Key findings of this thesis include the realization that traditional ice load evaluation methods may underestimate ice loads by not accounting for sea waves and hydrodynamic interactions. The novel BEM approach developed in this research provides a more accurate representation of these interactions, leading to better predictions of ice loads. The study also reveals that the impact of wave-induced motions is more pronounced than that of added mass. This research makes significant contributions to maritime engineering by uncovering the influence of hydrodynamics on ice load evaluations. It provides valuable insights for the design and operation of ice-going ships, ensuring safer navigationin ice-infested waters.