A coarse-grained discrete element method based on the principle of energy density mapping conservation: Efficient simulation of particle dynamic mixing and interaction using larger particles.

This article presents a novel coarse-grained methodology for discrete element method (DEM) simulations of particle materials, based on energy density mapping conservation. The approach ensures conservation of kinetic, elastic strain, frictional, and damping energy densities between the original fine-particle system and the coarse-grained system, enabling accurate scaling of microscopic interaction parameters when particle sizes are increased by a factor N. Validation through numerical simulations of dynamic particle mixing in a rotating drum and quasi-static direct shear tests demonstrated that the coarse-grained model preserves key mechanical behaviors—including velocity fields, stress distributions, mixing indices, shear rates, and force chain patterns—more faithfully than simulations without coarse-graining, especially at larger particle size ratios. The study establishes specific scaling laws for contact model parameters, such as stiffness and damping coefficients, and confirms the method’s effectiveness in improving computational efficiency while maintaining simulation accuracy for both rapid flow and quasi-static granular interactions.