标题： 瞬态导热理论 显示英文标题

标题： Theory of Transient Heat Conduction

摘要： 超快和纳米尺度的热传导需要一个统一的理论框架，该框架能够严格连接宏观输运方程与源自统计物理的微观材料特性。现有的傅里叶定律的经验推广往往缺乏坚实的微观基础，无法将观察到的非傅里叶行为与原子尺度的基本机制联系起来。 在这项工作中，我们提出了一个基于Zwanzig不可逆过程统计理论的时间域瞬态热传导理论。 这一框架的核心是通过热量流平衡时间关联函数定义的时间域输运函数 Z(t)。 此函数推广了常规稳态导热概念，控制着从有限速度下的二次声波传播到扩散主导行为在广泛时间和空间尺度上的转变。 与依赖于介观构造（如声子漂移速度）的声子水动力学模型不同，我们的方法提供了一种定量且微观描述瞬态热流内在记忆效应的方式，并适用于任意温度或长度尺度的块体材料。 通过将原子尺度的第一性原理计算与连续介质宏观方程相结合，这一框架为瞬态温度场的数值模拟提供了坚实的基础。 此外，它还促进了使用纳米级热源和极端紫外及X射线波段超快激光系统的瞬态热光栅实验的解释与设计，推动了我们对热耗散动力学的理解。 显示英文摘要

摘要： Ultrafast and nanoscale heat conduction demands a unified theoretical framework that rigorously bridges macroscopic transport equations with microscopic material properties derived from statistical physics.Existing empirical generalizations of Fourier's law often lack a solid microscopic foundation, failing to connect observed non-Fourier behavior with underlying atomic scale mechanisms. In this work, we present a time-domain theory of transient heat conduction rooted in Zwanzig's statistical theory of irreversible processes. Central to this framework is the time-domain transport function, Z(t), defined through equilibrium time-correlation functions of heat fluxes. This function generalizes the conventional concept of steady-state thermal conductivity, governing the transition of conduction dynamics from onset second sound type wave propagation at finite speeds to diffusion-dominated behavior across broad temporal and spatial scales. Unlike phonon hydrodynamic models that rely on mesoscopic constructs such as phonon drift velocity, our approach provides a quantitative and microscopic description of intrinsic memory effects in transient heat fluxes and applies universally to bulk materials at any temperature or length scale. By integrating atomistic-scale first-principles calculations with continuum-level macroscopic equations, this framework offers a robust foundation for numerical simulations of transient temperature fields. Furthermore, it facilitates the interpretation and design of transient thermal grating experiments using nanometer-scale heat sources and ultrafast laser systems in the extreme ultraviolet and x-ray wavelength ranges, advancing our understanding of heat dissipation dynamics.