Study On Convective Heat And Fluid Flow In A Channel Partially Filled With Porous Medium

Fluid flow and heat transfer phenomenon on the composite area of porous media and fluid was so widespread in nature and human society.The study on forced flow in porous media channels has important use value and practical significance on the agricultural product storage, environment pollution, building insulation and chemical production and other projects.In recent years, more and more scholars researched the mechanism of heat and mass transfer on the composite area of porous media and fluid,while there were only a few theoretical and experimental studies on the interface between porous media and fluid.Flow and heat transfer of the interface had very distinct effect on flow and heat transfer of the interface,so the intensive study of the interface between porous media and fluid has high scientific value,which provides a theoretical reference for the macroscopic mechanism of heat and mass transfer.Velocity of flow,the property of porous media had obvious influence on the fluid flow and heat transfer in the channel.More of the existing research focus on the impact of macro temperature field and velocity field,the number of research of slip effect was small The article had carried on the theoretical analysis of forced flow in porous media channels, made mathematical representations of the physical model, established mathematical model of forced flow and solved it by FEM.Using computed tomography (ct) scanning technology, the article construct real porous media model, study the numerical simulation of channels that are filled with humanly constructed and actual porous media respectively. Sponge and other porous materials were chosen as samples of numerical simulation, whose interior structure were scanned by computed tomography and processed by digital imaging.The MATLAB programs were used to filtering, sharpening, binariza the scanned image, and the models of real porous media/fluid were constructed as geometric models that were imported to FEM software to calculate.The article study the velocity and temperature fields of porous media channels in various conditions by numerical simulation, further researched the mechanism of heat and mass transfer on the composite area, researched the influences of fill ratio of porous media φ, Darcy number, pore structure of porous media, thermal conductivity properties K, Reynolds number Re and heat flux q to fluid flow and heat transfer in channels intensively, analyzed the affects of various factors to stress jump effect and thermal slip characteristics on the interface between porous media and fluid.Combined with the geometric model and research focus, this paper made a PIV and PLIF pilot scheme about fluid flow and heat transfer characteristics in the partially filled porous media channel. The precision porous media can be constructed by the technology of 3D printing, and use the optical glass processing square channel, to obtain the slip characteristics of the interface between porous media and fluid by the method of Particle Image Velocimetry and Planar laser induced fluorescence.The results showed that:Proportion of filled with porous media (p, Darcy number, has obvious influence on the fluid flow and heat transfer in the channel.Improve the porous medium filling ratio within a certain range can significantly enhance heat transfer, Da also have obvious effects on the Nu of the wall; Change of structure of porous medium can enhance the heat transfer effect in the channel effectively;There has obviously influence of Re and Da on the the stress of slip effect in the interface region. The bigger the Re, the larger stress jump coefficient was; The stress jump coefficient inversely with the Darcy number;The thermal slip characteristics of interface weakening gradually with the increase of the channel wall heat flux Q and thermal properties of porous media K.This paper studied the influence of factors on the flow and heat transfer in the numerical simulation by finite element method, to get the influence of various parameters on the nterface slip effect, provided a reference for the further study of forced convection heat transfer mechanism provides reference.