Influence of the geometric characteristics of media on the transition from Darcy to non-Darcy flow

Non-Darcy flow in pore media is a central challenge for subsurface energy extraction and geological conservation, and the effects of medium geometry features on the transition from Darcy to non-Darcy flow regimes in single-phase flow have not been comprehensively studied. This study quantitatively analyzed the impact of medium geometry features on the flow regime transition from the pore scale by constructing a series of two-dimensional models with different medium geometry features (particle disorder, particle radius, particle shape, and particle alignment angle). The results show that the geometric features influence the Darcy permeability and the flow regime transition by modulating the viscous dissipation rate of the system. With increasing disorder, a decrease in the particle radius, and a decrease in the number of polygonal edges, the system will enter the non-Darcy flow regime earlier. In addition, we analyze the intrinsic connection between vortices, the inertial core region, and medium geometrical features in the non-Darcy flow regime by introducing a typical pore–throat model. The non-Darcy flow regime transitions from a vortex-dominated state to an inertial core region-dominated state as the azimuthal angle of the medium pore increases.