基于D3Q19晶格的纳米硅薄膜超快传热特性研究

Research on ultrafast heat transfer properties of nano-silicon thinfilms based on D3Q19 lattice

中文关键词: D3Q19晶格  纳米硅薄膜  超快激光  热波  边界条件

英文关键词: D3Q19 lattice  nano-silicon thin film  ultrafast laser  thermal wave  boundary condition.

中文摘要:

      针对超快激光诱导的瞬态高温会引起三维纳米薄膜内复杂的热传导过程。设计了一种晶格玻尔兹曼法中的D3Q19晶格,研究了超快激光照射下纳米硅薄膜的热传导规律。重点分析了薄膜特征尺寸和边界条件对热传导的影响。研究结果显示,声子的有限传播速度导致能量在薄膜内积累,形成了五种传播速度相同的热波,在沿X方向和Y方向,分别会出现两个热波,在沿Z方向中,会出现一个热波,且受超快激光能量密度传播方向的影响,Z方向相对于X(Y)方向的热波峰值较高。当薄膜的特征尺寸小于声子平均自由程时,边界条件通过改变声子在界面处的透射和反射模式,在影响波的行为方面起到至关重要的作用。当热波到达无量纲厚度Z*为0.4时,此时波峰处的温度在三种绝热边界条件下(镜面、反弹和漫反射)分别为361.4K、345.9K和327.3K。因此,边界效应和系统尺寸对设计纳米材料、纳米器件以及其他尺度受限系统具有重要意义。

英文摘要:

      The lattice Boltzmann method with a D3Q19 lattice was designed to study thermal conduction in nano-silicon films under ultrafast laser irradiation. The influence of film characteristic dimensions and boundary conditions on heat conduction was analyzed. Results indicated that the finite phonon propagation velocity led to energy accumulation, forming five thermal waves with identical propagation speeds within the film. Along the X and Y directions, two thermal waves appeared separately, while along the Z direction, one thermal wave was observed, with its peak temperature influenced by the direction of laser energy density propagation. When the film"s characteristic size was less than the phonon mean free path, boundary conditions played a crucial role by altering phonon transmission and reflection modes at interfaces, affecting wave behavior. At a dimensionless thickness Z* of 0.4, temperatures at the wave peaks were 361.4K, 345.9K, and 327.3K under specular, diffusive, and semi-reflective boundary conditions, respectively. Therefore, boundary effects and system dimensions are crucial for designing nanomaterials, nano-devices, and other scale-limited systems.