This paper reports an experimental investigation of pressure-driven flow through models of porous media. Each model porous medium is a square array of circular acrylic rods oriented across the flow in a rectangular channel. The solid volume fraction φ of the arrays ranged from 0.01 to 0.49. Three boundary conditions were studied. In the first boundary condition, the model porous medium was installed on the lower wall of the channel only and was bounded by a free zone. In the second and third boundary conditions, porous media of equal and unequal φ were arranged on the lower and upper channel walls so that the two media touched (second boundary condition), and did not touch (third boundary condition). Using water as the working fluid, the Reynolds number was kept low so that inertia was not a factor. Particle image velocimetry was used to obtain detailed velocity measurements in the streamwise-transverse plane of the test section. The velocity data were used to study the effects of φ and the different boundary conditions on the flow through and over the porous medium, and at the interface. For the first boundary condition, it was observed that at φ = 0.22, flow inside the porous medium was essentially zero, and the slip velocity at the porous medium and free zone interface decayed with permeability. In the second and third boundary conditions, flow communication between the porous media was observed to be dependent on the combinations of φ used, and the trends of the slip velocities at the interface between the two porous media obtained for that boundary condition were indicative of complicated interfacial flow.

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the only published exact solution of the linear waterflood problem that includes capillary effects. Despite the importance of this breakthrough, their approach has largely been disregarded due to the perceived limitations that it presented in modeling real physical situations. In this article, we show that by appropriately normalizing relevant parameters of the governing equation involved, a substantial level of the limitations is taken care of. The resultant governing equation obtained is one in terms of a parameter N M related to the mobility ratio and another parameter N V , representing a ratio of the viscous to capillary forces. The results of the explicit solutions obtained indicate that these two parameters are indeed the controlling parameters of the flow, and that the capillary effects are practically non-existent even when N V = 100. These analytical results serve a very useful utility in validating numerical simulators.

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Baffles have long been known to be useful in enhancing heat transfer in channels with sudden expansions. However, their utility has been limited due to the increased differential pressure they incur in the flow. In this work, a pair of porous baffles is proposed to provide a solution to this problem. It is based on a finite-element numerical simulation of heat transfer and fluid flow through a two-dimensional channel with a backward-facing step. The baffles are modelled as matrices of two-dimensional rods arrayed downstream of the step, and on the top and bottom walls of the channel. Nondimensionalized parameters considered are the Reynolds number, Re (= 100 to 1000), normalized porous matrix location xp/S (= 0.5 to 6), normalized porous block length Lp/S (= 0.5 to 2.5), Darcy Number, Da (= 10 -2 to 10 -6 ), and normalized channel downstream length Ld/S (= 5 to 30). Results show that compared to the case of an unobstructed channel, the installation of porous baffles on both channel walls can generate up to 200% improvement in heat transfer. Optimal heat transfer effect with minimal differential power requirement is attained when the porous baffle length is half the step height S, and located 2S downstream from the step. Augmented heat transfer outcomes with minimal penalty of pressure drop are also reached at Re = 1000 and for Lu /H = 5. For such a case, for the same pressure drop requirement, convection to conduction heat transfer is 88% better when a pair of porous baffles are used, compared to an unobstructed flow.