Analysis On The Transition Layer Model At The Interface Between Porous Medium And Free Fluid

The partially filled porous medium composite system has good heat transfer performance and has extensive industrial applications.In view of the fact that the heat and momentum transfer at the porous/fluid interface has always been a difficult problem.In this work,the heat-momentum coupling problem at the interface of porous composite system is studied by using the transition layer model.In this work,the flow and heat transfer performance in a partially filled n-layer porous composite system under Couette flow and free boundary flow were analyzed.Darcy-Brinkman model was used for flow and local thermal non-equilibrium model for heat transfer in the study of the porous composite system under Couette flow and free boundary flow.In the selection of boundary conditions,except porous/fluid interface,all the intermediate interfaces adopt stress continuous boundary conditions.The analytical expressions of physical fields in the porous medium composite system under two flow modes(Couette flow and free boundary flow)are obtained by theoretical derivation.In addition,the related physical fields of the composite system partially filled with three layers of porous media are systematically analyzed based on the above results.In addition,based on the theoretical research results of the composite system under Couette flow and free boundary flow,the transition layer model is studied.Firstly,the analytical solution of velocity distribution of porous medium composite system with the transition layer is derived,and compared with the numerical solution of the micro-model of rectangular brush structure,the thickness of the transition layer is determined.The influence of the parameters on the thickness of the transition layer is studied,and the physical field of porous medium composite system is predicted by using the obtained parameters,and the error analysis is carried out.In addition,the theory of the transition layer model is combined with experimental date in Beavers and Joseph velocity slip models for porous medium composite system,and the optimal dimensionless transition layer thickness under different experimental conditions is obtained,and the influencing factors on the dimensionless transition layer thickness are further analyzed.The results show that: The deviation between velocity distribution of the transition layer model and the velocity numerical solution of the rectangular brush structure is very small.For Beavers and Joseph's experiments,the transition layer model can fit the experimental data well under the specific thickness of the transition layer,and the dimensionless thickness of the transition layer is independent of the thickness of the porous region.