能量守恒的耗散粒子动力学：等能积分与输运性质
Dissipative particle dynamics with energy conservation: isoenergetic integration and transport properties
AI总结：
针对DPDE方法现有积分算法的能量漂移问题，提出局部能量守恒的velocity-Verlet修改方案实现机器精度内总能量守恒，并推导热导率系数解析近似及Prandtl数和Schmidt数表达式，巩固了DPDE在温度不均匀介观系统研究中的稳健性。
摘要：
在热梯度下对纳米至微米尺度流体系统进行模拟，需要兼顾流体动力学相互作用和能量输运的相容介观方法。能量守恒的耗散粒子动力学（DPDE）便是其中之一，已用于各种温度分布不均匀的流体系统。尽管该方法取得了成功，但现有积分算法会导致不期望的能量漂移，令人质疑DPDE方法能否正确捕捉真实流体的性质。我们提出一种对velocity-Verlet算法的修改方案，使每个DPDE粒子的局部能量守恒，从而总能量在机器精度内守恒。此外，详细分析了DPDE流体的输运性质。特别地，推导了热导率系数的解析近似，允许先验地选择特定值。最后，给出了无量纲Prandtl数和Schmidt数的近似表达式，它们表征流体输运性质，可通过适当选择模型参数独立调整，从而与真实流体相当。总之，我们的结果巩固了DPDE方法作为研究温度不均匀介观系统的稳健方法。
英文摘要：
Simulations of nano- to micro-meter scale fluidic systems under thermal gradients require consistent mesoscopic methods accounting for both hydrodynamic interactions and proper transport of energy. One such method is dissipative particle dynamics with energy conservation (DPDE), which has been used for various fluid systems with non-uniform temperature distributions. Despite the success of the method, existing integration algorithms have shown to result in an undesired energy drift, putting into question whether the DPDE method properly captures properties of real fluids. We propose a modification of the velocity-Verlet algorithm with local energy conservation for each DPDE particle, such that the total energy is conserved up to machine precision. Furthermore, transport properties of a DPDE fluid are analyzed in detail. In particular, an analytical approximation for the thermal conductivity coefficient is derived, which allows the selection of a specific value a priori. Finally, we provide approximate expressions for the dimensionless Prandtl and Schmidt numbers, which characterize fluid transport properties and can be adjusted independently by a proper selection of model parameters, and therefore, made comparable with those of real fluids. In conclusion, our results strengthen the DPDE method as a very robust approach for the investigation of mesoscopic systems with temperature inhomogeneities.
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