From the micromechanics of Darcy’s law to particle-laden flows in porous media

¹ Department of Mechanical and Intelligent Systems Engineering, The University of Electro-Communications, Japan
² Department of Civil Engineering, Pelita Harapan University, Indonesia

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Published online: 1 December 2025

Abstract

We simulate flow in porous media using a two-dimensional combination of a DEM method (for the solid particles) and a FEM method (for the fluid). The fluid properties correspond to those of water, and porous domains are constructed by embedding fixed polygonal particles within a flow channel. By extracting subsamples of increasing size from a larger porous domain, we find a clear convergence from micro-geometry dependence to bulk behavior. This identifies the size of the Representative Elementary Volume (REV) of approximately 20 times the maximum particle diameter. We compare a disordered granular configuration with ordered square and staggered grid arrangements, all having the same porosity. The ordered systems exhibit higher permeability and more regular flow patterns, demonstrating the strong influence of pore structure on macroscopic flow. Our findings support the application of Darcy’s law for estimating pressure boundary conditions. This provides a basis for improving stability in future time-dependent simulations involving moving particles and evolving porous structures.