沉降分布孔隙率多孔介质模型及数值研究

研究沉降分布孔隙率多孔介质流动和传热,根据"O"形圈理论和现场测定确定孔隙率系数,建立坐标方向孔隙率分布函数;考虑流体密度变化,并引入Brinkman-Forchheimer的扩展Darcy模型,能量方程采用界面连续条件,建立沉降分布孔隙率多孔介质流动和传热求解模型.采用差分法对模型进行离散化,应用高斯-赛德尔方法迭代求解.数值分析表明:沉降分布孔隙率条件下多孔介质内流体流动速度在壁面附近较大,中心部位较小,壁面附近孔隙率的增大使得低流速区域减小,较高流速区域增大;当孔隙率小值时,温度按线性减小;当孔隙率大值时,温度在高低温壁面附近迅速减小,在中部减小较缓,热量按导热和对流共同传递;孔隙率增大能使平均怒谢尔数增大,对流换热作用增强.

Model of Porous Media with Settlement Distributed Porosity and Numerical Study

Flow and heat transfer in porous media with settlement distributed porosity is studied. Based on ‘O-shape’ ring theory and in situ measurement, a distribution function of porosity in x direction is established. Considering change of fluid density, Brinkman-Forchheimer-extended Darcy model is introduced. Energy equation is solved with continuity boundary conditions. A model of flow and heat transfer in porous media with settlement distributed porosity is established. The model is discretized with difference method. Gauss-Seidel iteration method is used. Numerical analysis shows that:Fluid flow velocity in porous media with of settlement distributed porosity is greater near wall surface, and it is small at center. Increase of porosity near wall surface reduces low velocity zone and increases high velocity zone. As porosity is small, temperature decreases linearly. As porosity is large, temperature near high and low temperature wall surface reduces rapidly. The decrease becomes slower at center. Heat is transferred through conduction and convection together. Increase of porosity increases average Nusselt number and enhances heat convection.