Experimental investigation of porous medium structural effects on a coupled porous media-free zone laminar flow

Abstract

An experimental research program was conducted to investigate the effects of solid volume fraction, arrangement of rods, and rod shape on slow flow through and over two-dimensional model porous media. The porous media were modeled using in-line and staggered arrays of rods of circular and square cross-sections to cover a range of solid volume fraction of 0.06 to 0.49. Each model was installed into a test section so as to fill three-quarters of the total depth of the flow section; and the flow was driven through the test section by pressure. Using a refractive-index matched viscous fluid, the bulk Reynolds numbers for the respective test conditions were kept considerably lower than unity. Particle image velocimetry measurements were made across the streamwise-transverse plane of the test section. Results indicate that the flow through the free zone increases from 75% to nearly 100% as the solid volume fraction increases from 0.06 to 0.49. While the bulk distribution is independent of the shape of the rods, or the mode of arrangement, at the interface, penetration of the free flow is dependent on the solid volume fraction and arrangement of rods. The interfacial flow is predicted by a new formulation from which a boundary condition is derived which unlike others in the literature, is devoid of jumps at the interface. This work provides detailed experimental data and important predictive tools for validations of theoretical and numerical work.