Pieprzyk Sławomir, Brańka Arkadiusz C, Heyes David M, Bannerman Marcus N
Institute of Molecular Physics, Polish Academy of Sciences, M. Smoluchowskiego 17, 60-179 Poznań, Poland.
Department of Physics, Royal Holloway, University of London, Egham, Surrey TW20 0EX, UK.
Phys Chem Chem Phys. 2020 Apr 29;22(16):8834-8845. doi: 10.1039/d0cp00494d.
This work reports a new set of hard sphere (HS) thermal conductivity coefficient, λ, data obtained by Molecular Dynamics (MD) computer simulation, over a density range covering the dilute fluid to near the close-packed solid, and for a large number of particles (up to N = 13 1072) and long simulation times. The N-dependence of the thermal conductivity is shown to be proportional to N-2/3 to a good approximation over a wide range of system sizes, which enabled λ values in the thermodynamic limit to be predicted accurately. The fluid and solid λ can be represented well by the Enskog theory (ET) formula, λE, times a density-dependent correction term, which is close to unity for the fluid and practically constant for the solid. The convergence of the MD λ data back towards ET in the metastable fluid starts just above the freezing density. For the HS solid and dense fluid it was found that the thermal conductivity is nearly linear in pressure, as has been observed experimentally for a number of solids. Simple excess entropy scaling over the higher density fluid phase region was found, and Rosenfeld's exponential relationship can be fitted to the simulation data for the solid to a high degree of accuracy. The simulation analysis has revealed a number of new trends in the behaviour of the HS thermal conductivity which could be useful in building more accurate models for heat conduction in experimental systems.
本研究报告了一组新的硬球（HS）热导率系数λ的数据，这些数据是通过分子动力学（MD）计算机模拟获得的，涵盖了从稀流体到近密堆积固体的密度范围，涉及大量粒子（多达N = 131072）且模拟时间较长。结果表明，在广泛的系统尺寸范围内，热导率对N的依赖性与N的-2/3次方成正比，这使得能够准确预测热力学极限下的λ值。流体和固体的λ可以用恩斯科格理论（ET）公式λE乘以一个与密度有关的校正项来很好地表示，该校正项对于流体接近1，对于固体实际上是常数。在亚稳流体中，MD的λ数据向ET的收敛恰好在凝固密度之上开始。对于HS固体和稠密流体，发现热导率在压力下近似呈线性，这与许多固体的实验观测结果一致。在更高密度的流体相区域发现了简单的过剩熵标度关系，并且罗森菲尔德的指数关系可以高度精确地拟合固体的模拟数据。模拟分析揭示了HS热导率行为的一些新趋势，这可能有助于建立更精确的实验系统热传导模型。
