A Surrogate Model for Quantifying Hydrodynamic Forces on Coastal Structures under Uncertain Compound Flooding Scenarios

Extreme storm events can lead to flooding in coastal cities, introducing significant uncertainties in floodwater depths and wind-driven storm surges and waves. Flooding from these events exerts static loads as well as wave-generated cyclic hydrodynamic forces on coastal structures. Typically, flood impact assessments focus solely on static water levels, overlooking dynamic load contributions. In addition, most numerical methods are computationally expensive when accounting for dynamic wave action due to the inherent complexity of accurately modeling such interactions, while empirical formulas tend to under- or over-estimate these dynamic load patterns. This research proposes a physics-based surrogate model to estimate hydrodynamic loading on residential buildings subjected to compound flooding from the combined effects of storm surge and waves. The surrogate model, based on Polynomial Chaos Expansion (PCE), aims to estimate fluid forces on these buildings under uncertain water levels and wave loads. The proposed methodology lays the foundation for scalable assessment of wave-induced loads in compound flooding scenarios by significantly reducing computational effort and has the potential to support future applications in coastal risk analysis, building fragility assessment, and resilience-oriented design.

Keywords: Computational Fluid Dynamics (CFD), Polynomial Chaos Expansion (PCE), Uncertainty Quantification, Residential Buildings, Compound Flooding.