Contact force model including the liquid-bridge force for wet-particle simulation using the discrete element method

The handling of wet particles in chemical engineering is often difficult because cohesive forces acting on wet particles cause particulate aggregation and the adherence of devices, unlike what occurs under a dry condition. The liquid-bridge force is introduced to the discrete element method in the investigation of the behavior of wet particles. However, existing numerical modeling has problems from the viewpoint of the effect of cohesion in contact states. Specifically, the cohesive force is treated as a constant value for contact states. This means the effect of the cohesive force is not only dependent on the spring constant in the discrete element simulation but is also frequently overestimated. To solve this problem, the present study developed a numerical contact model considering quantitatively the effect of the cohesive force in contact states and validated the model for a pan pelletizer. The behaviors and cascading angles of wet particles in simulation and experiments were in good agreement and the validity of the contact model was thus demonstrated. The present numerical contact model is thus a promising model for the numerical simulation of wet particles.