Fluid-structure interaction is a prevalent phenomenon in nature, particularly significant in coastal engineering, where the interactions between coastal waves and structures are crucial. Coastal defenses, such as breakwaters, often consist of large, irregularly shaped rock units, which pose challenges for conventional modeling approaches. This thesis addresses the need for a robust modeling technique that accurately simulates wave-structure interactions while representing particle irregularities in detail. It focuses on two primary studies: wave transmission through an offshore breakwater and the generation of impulse waves from a granular collapse. The research integrates fully resolved Computational Fluid Dynamics (CFD) with a Signed-Distance-Field-based Discrete Element Method (DEM)...[ Read more ]

Fluid-structure interaction is a prevalent phenomenon in nature, particularly significant in coastal engineering, where the interactions between coastal waves and structures are crucial. Coastal defenses, such as breakwaters, often consist of large, irregularly shaped rock units, which pose challenges for conventional modeling approaches. This thesis addresses the need for a robust modeling technique that accurately simulates wave-structure interactions while representing particle irregularities in detail. It focuses on two primary studies: wave transmission through an offshore breakwater and the generation of impulse waves from a granular collapse. The research integrates fully resolved Computational Fluid Dynamics (CFD) with a Signed-Distance-Field-based Discrete Element Method (DEM) to examine wave-structure interactions in high detail. This combination enables accurate modeling of the irregular shapes of rock particles and their influence on hydraulic responses. The modeling method is validated by comparing empirical formulas and existing data from the literature. Subsequently, the analysis of wave-structure interactions is conducted using the numerical solver, providing insights into how particle shape affects wave dynamics. The findings demonstrate that particle shape significantly impacts wave dissipation in breakwaters, particularly influencing wave reflection and transmission. Inaccurate modeling of particle shape can lead to overestimation or underestimation of critical parameters. In scenarios of granular collapse, particle shape greatly affects the transferred energy and resulting wave amplitude by influencing the collapse speed and particle runout length. Overall, the results indicate that the SDF-based CFD-DEM numerical model is a promising tool for providing more accurate insights into fluid-structure interactions.

Keywords: coastal engineering, CFD-DEM, particle shape, granular collapse, wave-structure interaction