Bulk properties of a porous media comprising randomly packed spherical particles without wall effects
M. Mohib Ur Rehman, Ari Seppälä · Powder Technology · 2026
The bulk properties of porous media such as bulk porosity, tortuosity and permeability are of fundamental importance for the prediction of fluid transport in natural and engineered systems. Porous media composed of randomly packed spheres are well studied, yet experimental correlations for bulk porosity and tortuosity often include wall effects cause by boundaries, while analytical modelling remains challenging. This study introduces new simulation-based empirical correlations to predict bulk porosity and tortuosity without wall effects. In this regard, random dense packings with various particle dispersions and distribution were generated using discrete element method (DEM) based simulations and regions within 0.5–1.5 particle diameter of the outer boundary of domains were removed. The bulk porosity (ε b ) was determined from the resulted domains of 3D packings and the bulk tortuosity (τ b ) was calculated with COMSOL Multiphysics simulations using diffusion model. The fitted data reveals that the ε b ranged from ∼0.32 to ∼0.40 and increased with the ratio of particle to the apparent column diameter (d m /D). In contrast, the τ b decreased from ∼1.70 to ∼1.52 with increasing ε b . The role of dispersion type showed a negligible influence on prediction of ε b and τ b for the parameters considered in this study. New empirical correlations for ε b and τ b were developed with less than 5 % fitting error. Validation under creeping flow ( Re = 1) showed that the bulk permeability (k b ) predicted using newly developed correlations without wall effects matched numerical results, whereas existing wall-affected models overestimated the values.