Numerical Simulation On Fluid Flow And Heat Transfer In A Channel Saturated Regular Array Porous Media

As porous media is widely used in daily life and industry, people pays more attention to it, to improve the heat transfer capacity for porous media, the pressure drop will increase greatly in the same time, therefore, the characteristics of flow and heat transfer has become the needs of many industries.In this context, water and power-law fluid flow in porous media were studied by using the software Fluent in this paper.The analysis results of flow characteristics is following, the mixing way between fluid changes over the speed of fluid, when speed is small, there are two symmetrical vortex in vortex area and there are no mixing phenomenon between fluid, as the velocity increases, the fluid occur fixing phenomenon, as velocity continues to increase, the streamline and flow beam of mixing fluid change both, the fluid mixing degree also increases with the increase of velocity. Power-law index n affect the shear stress and the weighted average speed of fluid in porous media, the shear stress increases and average speed decreases as the value of n decreases. When the porosity?particle diameter or the value of n decreases, the pressure drop of fluid flow in porous media will be greater. The characteristics of fluid flow in porous media is more sensitive to the bigger value of n, the influence decreases as the value of n decreases, when the value of n is less than or equal to 0.5142, the change of n has little influence on the flow characteristics and the phenomenon is more apparent as the velocity is bigger. The change of porosity will influence the accuracy of the values of A and B in the correlation about fm and Rem, but the value of A and B will not change as particle diameter is different. Drag-reducing phenomenon happens in the turbulent flow while the power-law index n is smaller and the velocity is bigger, the critical value of velocity decreases as porosity decreases.The analysis results of heat transfer characteristics is following, heat flux of the first row copper between the ball and the surrounding fluid roughly shows a trend of decrease on the flow direction, while the second row and the third row roughly show a trend of increase; the temperature difference between copper and surrounding fluid is similar with the changing rule of the heat flux. The convective heat transfer coefficient hsf keeps the same basically on the flow direction, the value of hsf increases as the velocity or the value of n increases or the particle diameter decreases. When the porosity or particle diameter decreases or power law index n, d/D or the solid heat conduction increases, the heat transfer ability in porous media will be stronger. The heat transfer coefficient hw in porous media is more sensitive to the bigger value of n, the influence decreases as the value of n decreases, when the value of n is less than or equal to 0.5142, the change of n has little influence on the value of hw and the phenomenon is more apparent in the condition of bigger velocity or smaller diameter or smaller porosity, which is similar to the flow characteristics. In addition, this paper gives the correlation about Nuw and ReD which is suitable for water and power law fluid and the applicable scope of correlation were summarized. The comprehensive heat transfer ability of model 1 is the biggest and the model 4 is the smallest, the comprehensive heat transfer coefficient will reduce when the diameter decrease from 13.55mm to 7.1mm or power law index n decreases.