论文标题
非局部热传输的时空依赖性热导率
Space-time dependent thermal conductivity in nonlocal thermal transport
论文作者
论文摘要
非局部热传输通常由PEIERLS-BOLTZMANN转运方程（PBE）描述。但是，由于整数差异方程的高维度，解决普通时空依赖性问题的PBE仍然是一项具有挑战性的任务。在这项工作中，我们使用特征分类方法对时空依赖性PBE提出了直接解决方案。我们表明，存在将热通量与局部温度联系起来的广义傅里叶类型关系，并且该构型关系定义了取决于时间和空间的导热率。将这种方法与声子特性的从头算计算相结合，我们证明了依赖时空的导热率在高热导率材料中的瞬时光栅几何形状中导致温度的振荡响应。目前的解决方案方法使我们能够扩展我们的计算能力以进行热传导到时空依赖于非时空的非造型运输方案。这种能力不仅可以更准确地解释热测量值，这些测量值可以观察到非局部热传输，而且还可以增强我们对高热导率材料中非局部热传输的物理理解，这些材料是纳米级热管理应用的有希望的候选者。
Nonlocal thermal transport is generally described by the Peierls-Boltzmann transport equation (PBE). However, solving the PBE for a general space-time dependent problem remains a challenging task due to the high dimensionality of the integro-differential equation. In this work, we present a direct solution to the space-time dependent PBE with a linearized collision matrix using an eigendecomposition method. We show that there exists a generalized Fourier type relation that links heat flux to the local temperature, and this constitutive relation defines a thermal conductivity that depends on both time and space. Combining this approach with ab initio calculations of phonon properties, we demonstrate that the space-time dependent thermal conductivity gives rise to an oscillatory response in temperature in a transient grating geometry in high thermal conductivity materials. The present solution method allows us to extend the reach of our computational capability for heat conduction to space-time dependent nondiffusive transport regimes. This capability will not only enable a more accurate interpretation of thermal measurements that observe nonlocal thermal transport but also enhance our physical understanding of nonlocal thermal transport in high thermal conductivity materials that are promising candidates for nanoscale thermal management applications.
