Multiresolution Modeling of Floods: Integrating Widely Graded and Arbitrary-Shaped Debris

Floods frequently transport hazardous debris of varying sizes and shapes—such as vehicles, wood, boulders, and construction materials—which complicate accurate flood modeling and prediction. To address this challenge, we propose a multiresolution framework that couples computational fluid dynamics (CFD) with the discrete element method (DEM) for multiphase flood simulation. The framework incorporates three modules: resolved, unresolved, and mixed-resolved-unresolved CFD-DEM, each designed to model debris at different scales. The resolved module captures detailed fluid–solid interactions for arbitrarily shaped objects, allowing high-fidelity simulation of floods carrying vehicles, wood, and boulders through forested areas. Object shapes can be digitized from scaled samples using X-ray CT or smartphone-based scanning. In contrast, the unresolved module enables full-scale simulation of debris-laden floods over complex terrains, supporting analysis of flood impacts on bridges and mitigation structures. Enhanced by GPU acceleration, this multiresolution CFD-DEM framework offers a unified approach to modeling multiscale, multiphase flood systems, improving the understanding and prediction of flood dynamics and mitigation strategies. As a novel contribution to flood modeling, the framework holds potential for broader applications in natural, engineering, and industrial contexts involving fluid–solid systems across scales. Acknowledgement: This research was supported by the NSFC Young Scientists Fund (Type C, No. 52508410).

Figure 1 Multiresolution multiphase CFD-DEM modeling of flood debris