Impact of tsunamis on buildings in array layouts as macro roughness: lessons from the 2018 Anak Krakatau event through DualSPHysics modeling

Coastal regions, facing rapid urbanization and increasing population density, are highly vulnerable to tsunamis, which can cause severe damage to infrastructure along shorelines. Despite the known risks, rebuilding efforts often occur in the same vulnerable areas without significant relocation. This study uses the DualSPHysics model, known for its precision in simulating complex fluid dynamics, to analyze the interaction between tsunamis and building models, specifically focusing on scenarios inspired by the 2018 Anak Krakatau Volcano tsunami. Six different layout scenarios of buildings, treated as macro-roughness elements (MRMs), were tested to explore their impact on tsunami forces. Model verification was conducted using laboratory data on tsunami forces acting on single and array models to ensure accuracy. The study identifies two primary mechanisms through which MRMs affect tsunami forces on a primary structure: shielding, which reduces direct wave impact and structural damage, and shadowing, which modifies wave reflection and flow patterns, thereby decreasing the overall force on the structure. These insights highlight the critical role of MRM placement in mitigating tsunami-induced forces, offering valuable guidance for enhancing coastal infrastructure resilience. The findings contribute to developing effective tsunami risk mitigation strategies, informing building design, and improving post-disaster recovery planning, ultimately promoting safer and more sustainable coastal communities.