Physical Process-Based Entrainment Behaviour Modelling of Diluted Debris Flow Using SPH Incorporated with HBP-DP Approach

  • Ma, Yangfan (Kyushu University)
  • Asai, Mitsuteru (Kyushu University)
  • Han, Zheng (Central South University)
  • Chen, Guangqi (Hebei University of Technology)

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The investigation of interaction forces and coupling mechanisms in multiphase flows utilizing the Smooth Particle Hydrodynamics (SPH) method has become a popular research topic in recent years, particularly for its applications in engineering geology. The present study focuses on examining the physical process of entrainment between dilute debris flows and erodible bed sediment. The destructiveness of debris flows is directly proportional to the volume of mass transferred, and entrained material can accumulate multiple times its original volume along the trajectory. Although there have been several notable studies on multiphase liquid-sediment interactions and resuspension, previous modelling approaches cannot be directly applied to the interaction between debris flow and bed sediment due to the non-Newtonian nature of the fluid. The hybrid viscosity and suspension model solution differ significantly from that in pure water, and the particle modelling of large-scale complex terrain poses a significant arithmetic challenge. This paper presents a numerical method based on Smooth Particle Hydrodynamics (SPH) to simulate the progressive entrainment of dilute debris flows using the Herschel-Bulkley-Papanastasiou (HBP) rheological model [1]. The Drucker-Prager yield criterion is adopted as a constitutive model to calculate the yield state of the bed sediment [2], and the hybrid viscosity is determined based on the kinetic properties of the mixed particle flow. To validate the performance of the proposed model, the US Geological Survey (USGS) flume experiment is selected as a case study [3]. The simulation results demonstrate longer run-out distances and greater destruction of erodible scenarios. Moreover, the accurate simulation of erosion volumes enhances the reliability of the SPH particle method for assessing the hazards of debris flows.