应用D2Q9格子玻尔兹曼模型研究超快激光传热过程

Application of D2Q9 Lattice Boltzmann Method to study ultrafast laser heat transfer process

目前,硅薄膜以及超快激光加热技术已经广泛应用于微/纳米的电子器件,其导热机理的研究将对微/纳米电子系统的热管理具有重要的指导意义。采用二维D2Q9的格子玻尔兹曼方法(Lattice Boltzmann Method,LBM)模拟超快激光加热硅薄膜的声子输运,并比较了一维LBM获得的结果。结果表明:当薄膜的克努森数>0.1时,受到激光扰动后,其内部会出现热量的波状传递现象,波动的大小与薄膜的克努森数有关,且会逐渐趋于平缓;其一维结果中虽也可以捕捉到这种热波现象,但会过高地估计薄膜内部的能量密度,因此激光径向方向的影响是不可忽视的。

At present,silicon thin film and ultrafast laser heating technology have been widely used in micro/nano electronic devices,and the study of its thermal conductivity mechanism will be an important guide for the thermal management of micro/nano electronic systems.The phonon transport simulation of ultrafast laser-heated silicon thin films is carried out using the two-dimensional D2Q9 Lattice Boltzmann Method(LBM),and the results are compared with those obtained by one-dimensional LBM.The results show that when the Knudsen number of the film is higher than 0.1,there will be a wave-like heat transfer phenomenon inside the film after it is perturbed by the laser.The magnitude of the fluctuation is related to the Knudsen number of the film and it will be gradually leveled off.The thermal wave phenomenon can also be captured in one-dimensional results,but the energy density inside the film is overestimated.Therefore,the influence of the radial direction of the laser cannot be ignored.