Evaluating cohesive models in discrete element simulation through drawdown test with new assessment perspectives

This study explores the time-dependent and micro-to-macro behaviours of cohesive wet granules through discrete element simulation of a widely employed calibration procedure, i.e., drawdown test. Two distinct cohesive models, i.e., the Easo Liquid-Bridge (ELB) and simplified JKR (SJKR) are adopted. Their simulation results are not only validated with past experimental observations, but also compared with each other in multiple aspects. The results show substantial difference in time-dependent deformation and mass-volume change correlations characterised by the ELB and SJKR models, though they both show good agreement in bulk parameters with the experiment at final stage of drawdown test. Moreover, this study points out critical deviations in microscale features such as the contact network and porous structure that determines the macroscale responses under different concepts of cohesive contact. The results suggest new assessment parameters for modelling cohesive material and provide a deeper insight into the micro-to-macro understanding.