Permeability of lattice wicks fabricated by laser powder bed fusion

Additive manufacturing enables engineered heat-pipe wicks with tailored pore geometry yet reported permeabilities for laser powder bed fusion (LPBF) lattices vary widely because permeability is often extracted from pressure-drop data that span multiple flow regimes. This study measures the permeability of LPBF AlSi10Mg lattice wicks using water flow through sealed test sections and establishes a repeatable procedure to isolate the Darcy (viscous) regime prior to fitting Darcy’s law. Simple cubic (SC), body-centered cubic (BCC), and fluorite unit cells were fabricated with systematically varied unit-cell size to produce porosities of approximately 20–70%. Differential pressure was recorded over a broad range of Darcy velocities. Reduced pressure-drop and friction-factor–Reynolds number representations were used to identify the onset of inertial effects. Darcy-regime bounds were refined by selecting the near-horizontal reduced pressure-drop region and adjusting end points to maximize linear-fit quality while maintaining regime consistency. Permeability values obtained from Darcy-only fits are compared with those extracted from broad-range (Darcy–Forchheimer) fits, demonstrating that including inertial data can bias permeability by up to ∼ 53% depending on lattice topology and porosity. Across the tested range, permeability increases strongly with porosity and depends on topology, with simple cubic lattices generally exhibiting the highest permeability for a given porosity. Finally, geometry-specific permeability–porosity correlations are proposed for preliminary wick selection and capillary-limit modeling, with applicability limits tied to the tested porosity window and LPBF length scales. The results provide guidance for consistent permeability extraction and reporting for AM lattice wicks.