Numerical Study On Single Phase Flow And Heat Transfer In Porous Media With Lattice Boltzmann Method

Porous media is playing a decisive role in various fields,such as environment,energy.The research work of flow and heat transfer in it has a great significance,both in scientific inquiry and engineering application.Based on this point,in the thesis,LBM is used on mesoscopic scale to simulate flow and heat transfer in porous media with different structures on pore scale.Through the research work of the thesis,people could promote understandings of flow and heat transfer in porous meida.The major work of the thesis is as follows.1.Different two-dimensional LBM models and treatment schemes of boundary conditions are studied.On this basis,flow and heat transfer in two-dimensional simple structures are simulated,moreover,fundamental influence factors of flow and heat transfer are analysed.These research work lays a solid foundation for studying complex flow and heat transfer in porous media.The predicted results show that within the scope of parameters studied,the heat transfer performance worsens with the increment of fins height,fins spacing-to-width ratio,solid-to-fluid thermal conductivity ratio.2.Two-dimensional porous media is constructed by Image Processing Method(IPM)and Quartet Structure Generation Set(QSGS),respectively.Block-structured LBM is used to simulate flow in a two-dimensional channel partially filled with porous media.The predicted results show that within the scope of pressure drop studied,the Darcy law remains valid in porous media constructed by IPM and QSGS.Under any pressure drop,both the flux and the permeability of porous media constructed by IPM and QSGS increase with increasing porosity.Under the same porosity,the permeability of porous media constructed by IPM is greater than that of porous media constructed by QSGS.3.Different three-dimensional LBM models and treatment schemes of boundaryconditions are studied.Three-dimensional porous media is constructed by Sierpinski carpets and QSGS,respectively.LBM is used to simulate flow and heat transfer in a three-dimensional channel fully filled with porous media.The predicted results show that for flow,within the scope of pressure drop studied,the Darcy law remains valid in porous media constructed by Sierpinski carpets and QSGS.Under any pressure drop,the permeability of porous media constructed by Sierpinski carpets and QSGS increases with increasing porosity.Under the same porosity,both the mean velocity and the permeability of porous media constructed by Sierpinski carpets are obviously greater than those of porous media constructed by QSGS.For heat transfer,the average Nusselt number of porous media constructed by Sierpinski carpets and QSGS is approximately linear with Reynolds number,furthermore,it is essential to consider the influence of the porosity.Under the same Reynolds number,the average Nusselt number of porous media constructed by Sierpinski carpets is greater than that of porous media constructed by QSGS.