Multiresolution Modeling of Multiphase Geophysical Flows

Synopsis

Geophysical flows such as debris flows, avalanches and floods pose significant geohazards in mountainous areas, likely worsened by impending global climate change. The multi-phase and multi-scale nature of these flows shapes their initiation, transportation, erosion, impact and runout dynamics, and makes them challenging to predict and model. We present a multiresolution framework for modeling multiphase geophysical flows by coupling computational fluid dynamics with the discrete element method. Four modules, resolved, unresolved and mixed-resolved-unresolved, and GPU-accelerated CFD-DEM, have been developed to model multiscale and multiphase particulate systems at varying resolutions. For instance, the resolved module probes turbulent fluid-arbitrary-shaped solids-structure interactions in geophysical flows, enabling high-fidelity modeling of debris flows carrying driftwood and boulders against forests. Shapes of driftwood, boulders, and trees are captured from reduced-scale samples using X-ray CT techniques, and the CFD and DEM models utilizing the immersed boundary (IB) and signed distance field (SDF) methods, respectively. Conversely, the…