Calibration of a coupled SPH-DEM model for mixtures of water and irregularly shaped cohesionless bulk materials

Mixed fluid and particulate flows are central to many material handling and processing applications such as wet grinding mills, wet banana screens, and slurry transport which has led to an increased focus on using computer simulations to model these processes. An emerging simulation approach is the coupling between smoothed particle hydrodynamics (SPH) and discrete element method (DEM). While substantial progress has been made in developing and validating such models, systematic calibration of contact parameters for coupled SPH-DEM simulations remain limited. This study presents a dedicated calibration methodology for mixtures of water and irregularly shaped, cohesionless bulk materials using an SPH-DEM approach. A dual‑mode experimental programme is designed to characterise both dry and submerged samples, with emphasis on identifying suitable particle–particle sliding and rolling friction coefficients. The results highlight the influence of water on the bulk material’s flow behaviour and demonstrate that using multiple complementary experiments significantly narrows the admissible parameter space for each flow mode. It is found that contact parameters calibrated under dry conditions do not reliably transfer to submerged SPH-DEM simulations and therefore it is essential that separate calibration for dry and wet regimes be conducted for accurate modelling of fluid–solid mixture flows.