Flow and heat transfer mechanism in the vicinity of the interface between the porous and fluid layers

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A theoretical and experimental study has been conducted to invesitigate the flow and heat transfer mechanism associated with the interface between the fluid layer and the fluid-saturated porous layer. A vertical plate with stainlesss foil surfaces was placed in the fluid and porous layers and heated up by supplying electric power through the stainless foils. The temperature filed in the vicinity of the interface, visualized by the Mach-Zehnder interferometer, reveals that the temperature gradient changes abruptly at the interface, and a hot spot appears near the corner where the flow recirculates. Thus, it has been demonstrated that the temperature field near the interface can be visualized effectively by means of Mach-Zhender interferometer. Unsteady flows around a porous square rod were also investigated using a hot wire anemoseter and smoke-wire flow visualization device. Base pressure, drag coefficient and Strouhal number were measured changing Reynolds and Darcy numbers. It has be … More en found that the flow passing through the porous rod forms a forward flow region, pushing the recirculationg zone downstream. The Strouhal number appears to be fairly insensitive to the Reynolds and Darcy numbers, and remains almost constant within the experimental range. It is also found that the forward flow region expands, and push the recirculation zone farther downstream, as the Reynolds number increases, while the darg coefficient decreases as increasing the Darcy number. Transient flow and heat transfer through a vertical fluid-saturated porous column was also investigated theoretically and experimentally, . The porous column of small beads was connected to the water tank which was controlled to, keep a. constant pressure head. A tungsten wire circuit synchronized with the valve placed at the bottom of the column was used to produce hydrogen bubbles. The bubble notion was monitored by a high speed camera, and analyzed to find the instantaneous velocity by a film motion analyzer. A onedimensional non-Darcy flow model has been proposed and the numerical results are compared against the experimental data to substantiate the validity of the model. The model reveals that the non-Darcy Porous inertia works to decrease the velocity level and the time required for reaching the steady state velocity level, and this time constant depends strongly on the perseabilty, irrespectively of the difference in the pressure head.Thus, the unsteady flow behavior in porous media and the flow and heat transfer characteristics associated with the interface between the porous, and fluid layers have been fully explored through the present study. Less