Validation of the generalized coarse-graining model in multi-particle simulations

Coarse-grained models are widely used to accelerate discrete element method simulations. For polydisperse particle systems, the number of particles increases with the cube of the particle size ratio. Traditional coarse-grained models cannot reduce the huge computational cost caused by the increase in particle size ratio because they use the same scale to scale particles of different sizes. To solve this problem, a variable-scale generalized coarse-grained model is proposed based on the consistency of the dimensionless contact equation, includes a new model named the constant surface energy (CSE) model, alongside the existing constant relative overlap (CRO) and constant absolute overlap (CAO) models. The applicability of the variable-scale generalized coarse-grained model in multi-particle simulations is verified through the angle of repose and uniaxial compression process. The CRO and combined CSE-CRO models show better consistency with the original bed using uniform and variable scaling ratios, respectively. The results show that the CSE-CRO model can reduce the calculation time by about 80% when the small particle scaling ratio is 2, and the mean relative error is less than 2%.