Permeability model of micro-metal foam with surface micro-roughness

We present an analytical model capable of predicting permeability for isotropic and fully saturated micro-open-cell metal foam with surface modified by micro-rods (30–50 μm). The analytical model is based on the pore-scale volume-averaging approach and the assumption of piece-wise plane Poiseuille flow with the reconstructed three-dimensional cubic unit cell having cylindrical micro-rods synthesized on the cell walls. Both of the metal foam structure and the randomly distributed micro-rods are assumed to be periodic. The proposed model includes both the macroscopic and microscopic parameters that characterize the metal foam as well as the micro-roughness. The effects of micro-rod radius, height and interval on permeability and tortuosity are examined. To validate the present analytical model, experimental results are employed and good agreement is found. Results demonstrate that the micro-rods synthesized on the cell walls significantly decrease the permeability of the micro-foam. The increase in micro-rod radius/height or decrease in rod interval makes the metal foam surface rougher and thus decreases the foam permeability.