The Study On Natural Convection And Heat Transfer In The Composite Cavity Of Porous Medium Fluid

The composite system of porous media and fluid prevail in nature phenomena, life, industrial and agricultural production. Natural convection and heat transfer phenomena which is related to the system can also be seen in many area, such as the use of nuclear energy, solar collector tubes, fuel cell, the process of solidification, micro-electronic technology, thermal insulation of external wall in buildings, etc. so natural convection and heat transfer in the composite system of porous media and fluid flow have important value of application and study significance, more and more scholars both at home and abroad began to pay wide attention of it. Because of the complexity of the study on the flow and heat transfer in the composite system, the quantity of the works have been carried out on such issues are relatively small. Therefore, more and more deeply study and discussion should be paid for flow and heat transfer in the composite system, so as to provide the corresponding theoretical guidance for engineering practice.The flow field and temperature field coexist to form a multi-physics. There is regional stress slip effect on the interface between the porous media and fluid region, which have certain effects on flow and heat transfer. In this paper, based on the theoretical analysis of the subject, combining the experimental results and numerical simulation, and taking the regional stress slip effect on the interface between the porous media and fluid region into account. Then the one regional mathematical model is established, and the finite element theory is used to solve the mathematical model.Using X-CT technology to scan for real porous media. The composition of industrial X-CT scanning device. Establishing the experiment platform of the porous media structure study on X-CT system. The porosity of Four porous media material will be scanned, then we can obtain the curve to show the variation of the porosity, And to explore the changes of the porosity. The whole process and result of the real porous media images will be shown in this paper.Using the finite element theory to simulate the the natural convection and heat transfer in the composite cavity. Set a temperature difference between the left wall and the right wall, then we simulate and analyze the changes of the flow field and temperature field under different conditions. The basic law of heat transfer and natural convection will be obtained. Focuses on the the flow field and temperature field which is influenced by the changes of the porous media thickness and the Rayleigh number, and analyze the changes in the stress jump coefficient.Based on the macroscopic scale study of porous media flow problem, The study on the mesoscopic scale is carried out. By using the lattice Boltzmann method, to simulate the natural convection in a closed cavity partially filled with porous media, and analyze the influence on natural convection in the cavity of different parameters.There is also a brief introduction of the PIV technique. Describe the improvements of porous media model in detail.Through the numerical simulation and experimental study above, analyze the effect on the natural convection and heat transfer in the composite cavity under different porous media thickness and the Rayleigh number, and analyze the influence of the stress jump coefficient on the interface. This will lay a foundation for the future experimental and multiple scales simulation study on the natrual convection and heat transfer in the composite cavity.