LBM Simulation Of Flow And Heat Transfer In Microchannel

With the development of science and technology,microchannel heat transfer technology not only enters the automotive air conditioning,household air conditioning,air energy and other industries,but also has great development prospects in the microelectronics field,which has high operational performance requirements,such as aeronautics and astronautics,chemical biological engineering,etc.Based on this,the lattice Boltzmann method is used to simulate the sliding effect of gas in the microchannel,the influence of the geometry of rough element in the rough microchannel on the flow resistance and the gas-liquid two-phase separation in the microchannel.The LBM evolution equation,the boundary condition setting,the multiphase flow model,the setting of the relaxation time of the thin gas and the setting of the slip boundary conditions are introduced in this paper.Using different two-dimensional LBM models,the accuracy of the heat transfer law of the fluid flow in the LBM is verified,which lays the foundation for the next step of the study and the pressure is used.The pressure driven boundary is used to simulate the flow of gas in the microchannel.The difference between microchannel pressure and macroscopic pressure distribution is studied.The influence of Kn and inlet/outlet pressure ratio P_io on pressure distribution is studied.It is found that the pressure in the microchannel is nonlinear,which is obviously different from the pressure distribution in the macroscale channel.The influence of the geometric shape of rough microchannel on the flow resistance is studied.The Poisson number Po of rough microchannel is found to be significantly larger than that of smooth channels.The heat transfer capability of the model with a roughness element density of 0.5 is obviously lower than that of the other two models.With the decrease of relative roughness,the heat transfer capability in the microchannel is enhanced.The separation of gas and liquid two phases in the microchannel and the effect of the initial density of the system on the separation are studied.It is found that the formation of droplets and bubbles in the flow field is related to the initial density.