Topology-Dependent Permeability in Lattice Structures: Simulation and Analysis

This paper presents a detailed numerical investigation of fluid permeability in three lattice topologies: Cube, BCC-Z, and Octet. Using Computational Fluid Dynamics (CFD), a parametric study is conducted across a range of relative densities from 10% to 80% for each topology [limited to geometry constraint]. Each configuration employs a constant unit cell dimension of 10 mm, with solid volume fractions adjusted by varying strut thickness to achieve the target density. The internal fluid domain of each lattice is extracted and simulated under steady-state, laminar flow conditions using ANSYS Fluent. A uniform inlet velocity of 0.01 m/s is applied at the inlet face, while the opposing face is assigned zero-gauge pressure; the lateral boundaries are defined as no-slip walls. Streamline trajectories are exported and processed in MATLAB to calculate the mean fluid path length, which is then used in Darcy’s law to determine permeability. Results reveal a non-linear decrease in permeability with increasing relative density for all three topologies, accompanied by a corresponding rise in fluid path tortuosity. Comparisons show that the Cube lattice exhibits the highest permeability due to its relatively straight channels, while the Octet and BCC-Z lattices display reduced permeability and higher tortuosity arising from their more complex flow paths. This expanded investigation across multiple topologies highlights the strong influence of lattice geometry on transport resistance and establishes a validated CFD- streamline-based framework for future optimization studies in flow-regulated applications.