Experimental and numerical estimation of slip coefficient in a partially porous cavity

The paper reported an experimental investigation of natural convection flow in a two-dimensional cavity partially filled with a vertical porous layer. The porous layer consisted of circular cylindrical rods installed horizontally along the left wall of the cavity in a regular array. The porosity and permeability were kept constant but the Rayleigh number varied to simulate different flow conditions. The range of Rayleigh number was from 2.806 x 10(4) to 1.053 x 10(6). A saline solution having a refractive index similar to that rods and cavity was selected as the working fluid. Particle Image Velocimetry was used to conduct detailed velocity measurement in the cavity, in particular the velocity in the porous and at the porous/fluid interface. From the measurement, the value of slip velocity at the interface was determined. It was found that the slip velocity made dimensionlessly by the shear rate at the interface was independent of interfacial height in mostly flow region, and also the slip coefficient. As a result, an average slip coefficient, defined as a mean value of the coefficient along the direction of interfacial height, was presented in a range of 0.307 through 2.53 for the experiment. (C) 2012 Elsevier Inc. All rights reserved.