Permeability of structured porous media: numerical simulations and microfluidic models

In this study, the permeability of structured porous media with the microfluidic model is experimentally and numerically determined, and compared with the classic Kozeny-Carman (KC) equation. The Reynolds number (Re) varies from 0.83 to 142.98. It is observed that the threshold of the Reynolds number is 1. When Re is below the threshold, the permeability is independent of the Reynolds number. When Re is over this threshold, the viscous force plays a dominant role and the permeability decreases with the Reynolds number increment. The permeability also rises with the diameter increment. With the same micropillar diameter, the microfluidic model with a triangular pillar arrangement yields 4.5%–7.4% lower permeability than that with a square pillar arrangement. The tortuosity obtained by numerical simulation in the triangular-arrangement model is 5.1%–7.9% higher than that in the square-arrangement model. Based on the arrangement of micropillars, a tortuosity model is proposed for quasi-two-dimensional microfluidic models. There is an inverse relationship between permeability and tortuosity. In addition, the permeability generated by numerical simulation is consistent with that obtained experimentally. However, the permeability estimated by the classic KC equation roughly agrees with experimental results when the porosity is between 0.50 and 0.60. A model proposed in this study is suitable for predicting the permeability of microfluidic models. Furthermore, anisotropy induced by the tilt angle (0°–90°) of a model rectangular micropillar arrangement causes preferential flow and decreases the effective porosity. When the tilt angle increases from 0° to 90°, the tortuosity declines from 2.04 to 1.03, causing the permeability to rise from 1.0×10−11 to 4.3×10−11 m2.