The Lattice-boltzmann Modeling And Analysis Of Coupled Radiation And Convection Heat Transfer

Coupled radiation and convection heat transfer problems are widely used in engineering fields,such as: industrial forging process,air conditioning refrigeration cycle,high speed aircraft flight,high temperature combustion furnace operation,Infrared heating and cooling and so on.In practical engineering applications,the temperature is usually high,the radiation heat transfer process will have a significant impact on the heat transfer effect at this time,which can not be ignored.Therefore,a detailed study of the coupled radiation and convection heat transfer problem is of great significance.At present,the study of coupled radiation and convection heat transfer is mainly carried out by hybrid numerical simulation method.Among them,for the convective heat transfer problem,the study using the lattice Boltzmann method is hot,and other numerical simulation methods are used for the calculation of radiation heat transfer.The hybrid calculation of different numerical methods can cause cumbersome calculation and loss of calculation in the process of programming and calculation.Therefore,it is important to establish a unified form of LB equation to solve the coupled radiation and convection heat transfer problem.The main purpose of this paper is to establish a unified LB equation to solve the problem.In the paper,the lattice Boltzmann method is used to solve the radiative transfer equation.And the influence of radiation on the flow and heat transfer process in the coupled heat transfer problem is studied.The Chapman – Enskog analysis is used to establish the lattice Boltzmann equation for solving the radiative transfer equation.When the optical thickness is large,radiative transfer equation is the diffusion dominance equation,lattice Boltzmann method has second order convergence accuracy.With the decrease of optical thickness,radiative transfer equation gradually exhibits convection dominant characteristic,and lattice Boltzmann method convergence rate decreases accordingly.At the same time,the stability of the established LB equation for the Gaussian emission field problem and the applicability to the coupled heat transfer problem are also analyzed.Then,the radiation-convective coupled heat transfer process in the phase transition process is studied,and a unified lattice Boltzmann equation is established to solve the process.The effects of natural convective heat transfer and radiative heat transfer on the process were studied respectively.In the study of the effects of natural convective heat transfer on the phase transition process,the effects of different Prandtl numbers,Rayleigh numbers and Stephen number are analyzed.In the study of the effect of radiative heat transfer on the natural convection phase transition process,the effects of different Radiation parameters are analyzed.Then,the mixed convection-radiation heat transfer process in the study of magnetic fluid mechanics is analyzed,and a unified lattice Boltzmann equation is established to solve this process.The effects of magnetic field and radiative heat transfer on the mixed convection process are studied in both constant magnetic field and changed magnetic field.