3D SPH modeling of coal granular flow: Implementation and Scenario Validation

This study applies the Smoothed Particle Hydrodynamics (SPH) method, a mesh-less Lagrangian numerical simulation technique, to model and simulate the three-dimensional (3D) flow of coal particles during the coal mining process for the first time. The research focuses on the continuous and plastic flow behaviors of coal particles during the top coal caving and scraper transportation processes. The study introduces the fundamental principles and numerical implementation of the SPH method, including model initialization, differential operators, smoothing length selection, and solution algorithms. A 3D model for coal particle flow is constructed based on the elastoplastic soil constitutive model, along with a corresponding SPH solution process. A composite contact algorithm is proposed to simulate the interaction between the scraper and coal flow, ensuring coal particles do not penetrate solid boundaries. The model simulates coal drawing and transportation processes under different working conditions, providing distributions of key parameters such as velocity, stress, and plastic strain. Sensitivity analysis of SPH parameters is conducted, discussing the effects of smoothing lengths, particle spacing, and differential operators on numerical accuracy and computational efficiency. Results demonstrate that the SPH method accurately captures discontinuities and large deformations in coal particle flow, showing good consistency with experimental data. The non-cohesive soil constitutive model effectively simulates granular material flow, avoiding parameter uncertainty associated with traditional Discrete Element Method (DEM) models by setting material parameters like friction angle and elastic modulus. Additionally, the study analyzes the effects of parameters such as conveyor belt speed, coal pile height, friction angle, and density on coal flow behaviors, providing an effective numerical tool for optimizing coal mining and transportation systems.