Thermal conductivity calculation of nano-suspensions using Green–Kubo relations with reduced artificial correlations
Thermal conductivity calculation of nano-suspensions using Green–Kubo relations with reduced artificial correlations
复制标题
使用减少人工相关性的 Green-Kubo 关系计算纳米悬浮液的导热系数
DOI：
10.1088/1361-648x/aa5f08
复制
发表时间：
2017
期刊：
影响因子：
--
通讯作者：
Yang, Vigor
中科院分区：
文献类型：
--
作者：
Muraleedharan, Murali Gopal;Sundaram, Dilip Srinivas;Henry, Asegun;Yang, Vigor
研究了与绿-久保（GK）热导率计算相关的人工关联的存在。采用平衡分子动力学（EMD）方法，利用GK关系计算了纳米悬浮液的热导率。首先对分散在水介质中的单个氧化铝（al2o3）纳米颗粒进行了计算。当颗粒尺寸为1 nm，体积分数为9%时，结果显示增强高达235%，远远高于麦克斯韦模型的预测。当对多个悬浮粒子进行计算时，没有观察到这种异常增强。这是因为氧化铝晶体中的振动可以作为低频扰动，它可以通过周围的水介质传播很长的距离，其特征是更高的振动频率。作为周期边界的结果，它们重新进入系统，导致氧化铝颗粒与其自身图像之间的热波动产生圆形共振，最终导致热流自相关函数（HCACF）中的人为关联，当集成时产生异常高的导热系数。添加更多的粒子会出现“障碍”，在波动反馈到周期性图像之前，它们会与波动相互作用并消散。对HCACF时间演化的系统研究表明，随着悬浮纳米粒子数量的增加，人工相关的幅度和振荡显著减小。
The presence of artificial correlations associated with Green–Kubo (GK) thermal conductivity calculations is investigated. The thermal conductivity of nano-suspensions is calculated by equilibrium molecular dynamics (EMD) simulations using GK relations. Calculations are first performed for a single alumina (Al 2 O 3) nanoparticle dispersed in a water medium. For a particle size of 1 nm and volume fraction of 9%, results show enhancements as high as 235%, which is much higher than the Maxwell model predictions. When calculations are done with multiple suspended particles, no such anomalous enhancement is observed. This is because the vibrations in alumina crystal can act as low frequency perturbations, which can travel long distances through the surrounding water medium, characterized by higher vibration frequencies. As a result of the periodic boundaries, they re-enter the system resulting in a circular resonance of thermal fluctuations between the alumina particle and its own image, eventually leading to artificial correlations in the heat current autocorrelation function (HCACF), which when integrated yields abnormally high thermal conductivities. Adding more particles presents' obstacles' with which the fluctuations interact and get dissipated, before they get fed back to the periodic image. A systematic study of the temporal evolution of HCACF indicates that the magnitude and oscillations of artificial correlations decrease substantially with increase in the number of suspended nanoparticles.
登录
查看更多内容
影响因子：
4.4
作者：
D. Sundaram;V. Yang;Ying Huang;G. Risha;R. Yetter
通讯作者：
D. Sundaram;V. Yang;Ying Huang;G. Risha;R. Yetter
氧化铝纳米颗粒水悬浮液中的热传输
影响因子：
2.7
作者：
M. Muraleedharan;D. Sundaram;V. Yang
通讯作者：
V. Yang
影响因子：
7
作者：
Xuan Wu;Ranganathan Kumar;P. Sachdeva
通讯作者：
P. Sachdeva
DOI：
10.1016/0095-8522(55)90047-7
发表时间：
1955
期刊：
Journal of Colloid Science
影响因子：
--
作者：
S. Ross;W. Winkler
通讯作者：
W. Winkler
水化层和表面润湿性对增强纳米流体导热性的影响
影响因子：
4
作者：
P. Sachdeva;Ranganathan Kumar
通讯作者：
Ranganathan Kumar