Developed DNS-DEM coupling model for normal collisions of ellipsoidal particles on wet surfaces

In typical chemical engineering processes such as fluidized bed reactors, spray drying, and catalyst transport, a deep understanding of wet particle collisions plays a crucial role in explaining particle adhesion mechanisms, agglomeration, and liquid bridge formation. While numerous theoretical and empirical models have been developed to describe wet collisions of spherical particles, most particles in practical systems exhibit non-spherical geometries, and research on such cases remains very limited. Therefore, this study develops a DNS-DEM coupled model to simulate the liquid bridge dynamics involving non-spherical particles and multiphase flow. The gas-liquid boundary is captured using the Volume of Fluid (VOF) technique, and particle geometry is represented by a superquadric equation. Furthermore, by integrating the superquadric formulation with a quaternion-based method, a modified treatment of the three-phase contact line is implemented. The developed model systematically investigates the effects of particle aspect ratio, impact velocity, contact angle, and liquid viscosity on wet collision behavior. The results show that a larger aspect ratio increases the contact area and intensifies liquid bridge deformation, leading to a reduction in the restitution coefficient. In contrast, higher impact velocities enhance particle rebound, causing the wet restitution coefficient to increase and gradually approach a stable value. Additionally, the particle restitution coefficient exhibits a non-monotonic trend with contact angles, initially decreasing and subsequently increasing, reaching a local minimum around 70°. Additionally, the restitution coefficient decreases with increasing viscosity. This developed methodology is applicable to multi-particle systems without relying on empirical models such as drag or liquid bridge force formulations, thereby providing theoretical guidance for practical engineering applications.