论文标题

转子链中的热机械传输

Thermo-mechanical transport in rotor chains

论文作者

Iacobucci, Alessandra, Olla, Stefano, Stoltz, Gabriel

论文摘要

我们研究在边界上应用的热机械强迫下,温度和角动量的宏观曲线和角动量的固定状态。这些轮廓是通过热机械强迫确定的边界条件的扩散偏微分方程系统的解决方案。我们不是对基础微观动力学的昂贵蒙特卡洛模拟,而是基于描述宏观稳态的部分微分方程系统的有限差分方法执行了广泛的数值计算。我们首先根据线性响应论点和局部平衡假设对这些固定方程式进行形式推导。然后,我们研究这些方程的解决方案的各种特性。这允许表征导致上坡能量扩散的参数状态 - 在这种情况下,能量朝着温度梯度梯度流动 - 并识别与负能量电导率相对应的参数区域(即能量电流的正线性响应到温度梯度)。我们得出的宏观方程与通过微观物理系统的数值模拟获得的一些先前结果一致,这证实了它们的有效性。

We study the macroscopic profiles of temperature and angular momentum in the stationary state of chains of rotors under a thermo-mechanical forcing applied at the boundaries. These profiles are solutions of a system of diffusive partial differential equations with boundary conditions determined by the thermo-mechanical forcing. Instead of expensive Monte Carlo simulations of the underlying microscopic dynamics, we perform extensive numerical computations based on a finite difference method for the system of partial differential equations describing the macroscopic steady state. We first present a formal derivation of these stationary equations based on a linear response argument and local equilibrium assumptions. We then study various properties of the solutions to these equations. This allows to characterize the regime of parameters leading to uphill energy diffusion -- a situation in which the energy flows in the direction of the gradient of temperature -- and to identify regions of parameters corresponding to a negative energy conductivity (i.e. a positive linear response of the energy current to a gradient of temperature). The macroscopic equations we derive are consistent with some previous results obtained by numerical simulation of the microscopic physical system, which confirms their validity.

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