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A Novel Method for Fluid Pour-Point Prediction by Molecular Dynamics Simulations
Tribology Transactions ( IF 2.1 ) Pub Date : 2021-06-10 , DOI: 10.1080/10402004.2021.1910391
Jannat Ahmed 1 , Junqin Shi 1 , Jie Lu 1 , Ning Ren 2 , Frances E. Lockwood 2 , Q. Jane Wang 1
Affiliation  

Abstract

Pour point, or the temperature below which a fluid ceases to flow, is an important lubricant property. A molecular-dynamics-based approach is developed to explore and identify the pour points of a number of fluids. Diffusion behaviors of several fluids are investigated by time-averaged mean squared displacement (MSD), and a clear trend change of the MSD data is observed as a function of temperature. The temperature at this trend change corresponds well with the experimental pour point. Further, a correlation formula is obtained to link pour point and the ratio of the solvent accessible surface area (SASA), which is defined as the locus surface of the center of a solvent probe when it rolls over the surface of the fluid molecule, to the total number of carbon, in terms of SASA/Nc, and several molecular structural features. The pour points obtained from the molecular dynamics (MD) simulation and formula prediction are compared with existing experimental results, and the good agreement supports the proposed pour-point determination methods.



中文翻译:

一种通过分子动力学模拟预测流体倾点的新方法

摘要

倾点,或低于该温度流体停止流动的温度,是一种重要的润滑剂特性。开发了一种基于分子动力学的方法来探索和识别多种流体的倾点。通过时间平均均方位移 (MSD) 研究了几种流体的扩散行为,并观察到 ​​MSD 数据随温度变化的明显趋势变化。这种趋势变化的温度与实验倾点很好地对应。此外,获得相关公式将倾点和溶剂可及表面积(SASA)的比率联系起来,溶剂可及表面积(SASA)定义为溶剂探针在流体分子表面上滚动时的中心轨迹表面,以碳的总数,以 SASA/ N c 表示,以及几个分子结构特征。从分子动力学 (MD) 模拟和公式预测中获得的倾点与现有实验结果进行了比较,良好的一致性支持了所提出的倾点测定方法。

更新日期:2021-07-14
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