Non-Fourier heat conduction in a single-walled carbon nanotube: Classical molecular dynamics simulations
Non-Fourier heat conduction in a single-walled carbon nanotube: Classical molecular dynamics simulations
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DOI：
10.1103/physrevb.73.205420
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发表时间：
2006-05
影响因子：
3.7
通讯作者：
J. Shiomi;S. Maruyama
中科院分区：
文献类型：
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作者：
J. Shiomi;S. Maruyama
通过施加持续时间亚皮秒的局部热脉冲来研究单壁碳纳米管中的非稳态热传导。该研究基于经典的分子动力学模拟，其中通过将恒温器短时间连接到本地电池来产生相干波动的热脉冲。根据时空温度分布观察通过纳米管的热传导。模拟结果显示出非傅立叶热传导，其中大量热量以波状形式传输。碳纳米管的几何形状使我们能够在材料的实际尺寸中观察到这种现象。将所得的时空分布与可用的宏观方程（即所谓的非傅立叶热传导方程）进行比较，以研究唯象模型对准一维系统的适用性。由于缺乏局部扩散，传统的双曲扩散方程无法预测热传导。结果表明，可以通过采用双弛豫时间模型来解决这个问题。使用小波变换的进一步模态分析揭示了光学声子模式对观察到的波状热传导的显着贡献。结果表明，在长度有限的碳纳米管中，“长波长声子表现出弹道行为，甚至光学声子也可以在非傅立叶热传导中发挥重要作用。” less
Nonstationary heat conduction in a single-walled carbon nanotube was investigated by applying a local heat pulse with duration of subpicoseconds. The investigation was based on classical molecular dynamics simulations, where the heat pulse was generated as coherent fluctuations by connecting a thermostat to the local cell for a short duration. The heat conduction through the nanotube was observed in terms of spatiotemporal temperature profiles. Results of the simulations exhibit non-Fourier heat conduction where a distinct amount of heat is transported in a wavelike form. The geometry of carbon nanotubes allows us to observe such a phenomenon in the actual scale of the material. The resulting spatiotemporal profile was compared with the available macroscopic equations, the so-called non-Fourier heat conduction equations, in order to investigate the applicability of the phenomenological models to a quasi-one-dimensional system. The conventional hyperbolic diffusion equation fails to predict the heat conduction due to the lack of local diffusion. It is shown that this can be remedied by adopting a model with dual relaxation time. Further modal analyses using wavelet transformations reveal a significant contribution of the optical phonon modes to the observed wavelike heat conduction. The result suggests that, in carbon nanotubes with finite length wheremore » the long-wavelength acoustic phonons behave ballistically, even optical phonons can play a major role in the non-Fourier heat conduction.« less