Monte Carlo Simulation Of Thermal Transpor In Complex Micro-nano Systems

Micro-nano-scale heat transfer is an important research direction of thermal science in recent decades.Due to the integration of electronic components and the development of thermoelectric materials,the exploration of heat transport at micro-nano scale has become a major problem.In this paper,we use the improved Monte Carlo method to simulate phonon thermal conduction under different models.The accuracy of the method is verified by comparison with the existing analytical solutions.In addition,thermal transport in nanostructured materials is studied.By detailing the contributuion of each frequency to thermal conductivity,the effects of different pores distributions and porosity is analyzed deeply.It is found that the pores weakens the contribution of low-frequency phonons to thermal conductivity.The pores cause barrier effects on phonon propagation and vary greatly with their distribution.Thermal transport in nanoporous or nano-mesh structures is characterized by obvious ballistic processes.The shape and porosity have a great influence on the thermal conductivity.In the case of small porosity,the pore perimeter and the interface length perpendicular to the flux flow are the main factors.As the porosity increases,the shortest distance between the pores(neck)becomes the main factor.The shorter the distance,the smaller the thermal conductivity.Another important problem in complex micro-nanostructures is the interface transport.In theory,AMM and DMM are two traditional models for predicting interface thermal conductance,but only limited to completely specular interface or completely rough interface and correspond to the actual value in a small range.In this paper,the effects of different interface modes on thermal conductance and the specific reasons are studied.The specific factors affecting thermal conductance are analyzed.It is found that the processing method of low-frequency phonon and the important influence of transmission coefficient,and whether or not the phonon coherence is considered to have a great influence on the thermal conductance.It is found that KMC method has obvious advantages in solving the situation of semi-infinite large and very small temperature difference by simulating TTR experiment.