DEM study of wall effect through geometric features of the cylindrical and conical wall

Abstract This study investigates the influence of wall geometry (11 types) and friction on the structural, dynamic and kinematic characteristics of monodisperse, spherical granular systems in cylindrical and frustrated conical geometries, utilizing the 3D Discrete Element Method (DEM). Five porosity calculation methods—Volumetric Reconstruction (3D-SRV), Voronoi-based, Analytical, Localized Core-Zone (IZ-2), and Adaptive Radial Voronoi Profiling (ARVP)—were compared across five distinct spatial zones. The analysis included the quantitative investigation of particle–wall and particle–particle contact numbers, as well as the normal forces during the filling and relaxation (t > 1.0 s) phases. The global analytical method was found to overestimate the void fraction; in contrast, the IZ-2 and ARVP methods yielded values closely aligning with the theoretical Random Close Packing (RCP) limit of 0.363. Wall inclination increases the particle–wall coordination number and the normal forces exerted on the wall, while delaying velocity evolution. In the internal zones, patterned wall surfaces accelerate particle motion and result in a more uniform inter-particle force distribution. The 3D-SRV proved the most sensitive indicator of wall geometry variations. The results highlight the mechanical discrepancies between the filling process and slow consolidation, providing a basis for the spatial optimization of industrial containers.