Study On The Slip Effect At The Interface Of Complex Cavity Partially Filled With Porous Medium

Fluid flow, heat and mass transfer process in a complex cavity system partially filled with porous media exist in nature widely and has a wide range of applications in many science and engineering fields, including building engineering, drying process, petroleum engineering, bio remediation, mechanics, earth science, biology and physics, materials science, biological filter, metallurgy and chemical industry and so on, so it has a far-reaching influence on guiding the practical engineering application. The deeply study on the slip effect at the interface of porous media and fluid region has an important significance to master the law of fluid flow and heat transfer in the complex cavity partially filled with porous media.The paper adopts the method which is combination of theoretical analysis and numerical simulation to establish one domain mathematical models. To calculate the stress jump coefficient and thermal slip coefficient, and analyze the flow and heat transfer in the composite cavity partially filled with porous media, we can obtain the law of factors which have influence on the flow and heat transfer in the composite cavity. Brick is chosen as the porous materials, and then use the X-ray computer tomography (X-CT) to obtain the internal structure of porous media. Scanned images were filtered, sharpened, binarized and other processing by Matlab programming and reconstructed a complex cavity system partially filled with real porous media to simulate. In order to study the effect of porous medium layer structure on the flow and heat transfer in the complex cavity partially filled with porous media and explore the effect of each factor on the slip effect, the artificial structure of porous medium layer is filled into the complex cavity on the left. Compared with the complex cavity filled with real porous medium model, the results of the simulation show that the study on the slip effect at the interface in the complex cavity partially filled with porous media is reasonable and effective by using the artificial structure of porous medium model.In order to analysis the slip effect at interface further, the finite element method is used to study that the structure characteristics of porous media, the Rayleigh number and the fluid media impact on the velocity and temperature of partially fluid that filling into porous medium sealing compound cavity, and the influence of each factor on the slip coefficient are obtained. The results of the study suggest that, the thickness of the porous medium layer increases, the resistance of fluid flow in composite cavity increasing gradually, the flow rate decreasing, the effect of heat transfer weakening, and the stress jump coefficient showing a trend of decrease; the slip coefficient increases with the increase of the porosity of porous media, and the numerical changes are obviously; porous dielectric layer cylindrical structure arrangement has little influence on the stress jump coefficient; the whole stress jump coefficient shows upward trend with increasing Rayleigh number, and trends of the interface near the wall is more obvious when compared with the middle position, but the impact of temperature slip coefficient is relatively small; the whole stress jump coefficient shows upward trend with an increasing viscosity of the fluid motion, and the change in value is more obviously; with the increase of the coefficient of thermal conductivity of porous media materials, the whole temperature slip coefficient shows downward trend; the Prandtl number has little effect on the temperature slip coefficient at the interface of composite cavities.The key is to determine the slip effect in different structure of porous media, Rayleigh number and fluid medium, and analyze of the influence of the flow and heat transfer characteristics in interface region of the composite cavity on the natural convection heat transfer in the whole cavity, in order to study the mechanism of the slip effect at the interface region.