疏液壁面上亲液杂质对滑移特性的影响

发布时间：2018-01-30 21:02

本文关键词： 疏液表面亲液杂质滑移分子动力学　出处：《力学学报》2017年04期 　论文类型：期刊论文

【摘要】：纳米流动系统具有高效、经济等优势,在众多领域具有广泛的应用前景.因该类系统具有极高的表面积体积比,致使界面滑移效应对流动具有显著影响.论文采用非平衡分子动力学模拟方法,研究了疏液壁面表层混入少量亲液原子时纳米通道内液体的滑移特性,并基于分子动理论解释了其影响机制.研究发现,亲液杂质(均布或集中)对液体法向密度振荡程度影响较弱,但会显著改变壁面附近类固体层的分布和液体滑移规律;随亲液杂质占比增加,液体类固体现象更趋明显,壁面处液体接触密度也线性增大,但通道内液体平均速度逐渐降低,滑移长度也迅速减小;相比于集中的亲液杂质,均匀分布亲液杂质对滑移的弱化效应更强.如当亲液杂质占比为28%时,其滑移长度比单纯疏液表面的降低率从50%扩大至56%.基于分子动理论的分析发现,亲液杂质会导致杂质原子附近第一液体层内的原子发生跃迁的能垒加大,即弱化了液体原子的流向跃迁行为,从而降低了滑移量;相比于集中杂质,均匀分布的杂质还会降低固液间的非公度性,致使滑移特性破坏更严重.
[Abstract]:Nano-flow systems have many advantages, such as high efficiency, economy and so on, which have a wide application prospect in many fields because of their high surface area volume ratio. The non-equilibrium molecular dynamics simulation method is used to study the slip characteristics of the liquid in nanochannels when a small amount of hydrophilic atoms are mixed into the surface of the surface of the thinned liquid. Based on the molecular kinetic theory, the influence mechanism is explained. It is found that the hydrophilic impurity (uniform or concentrated) has a weak effect on the degree of normal density oscillation of liquid. However, the distribution of solid layer near the wall and the law of liquid slip will be changed significantly. With the increase of the proportion of lipophilic impurity, the phenomenon of liquid solids becomes more obvious, the contact density of liquid increases linearly at the wall, but the average velocity of liquid in the channel decreases gradually, and the slip length decreases rapidly. Compared with concentrated hydrophilic impurities, uniform distribution of hydrophilic impurities has a stronger weakening effect on slippage, such as when the proportion of hydrophilic impurities is 28%. The slip length decreases from 50% to 56. Based on the molecular kinetic theory, it is found that the slippage length is lower than that of the pure liquid surface. Hydrophilic impurity increases the energy barrier of the transition of atoms in the first liquid layer near the impurity atom, that is, weakens the flow direction transition behavior of the liquid atom, thus reducing the slip. Compared with concentrated impurity, uniformly distributed impurity can also reduce the inconsistency between solid and liquid, resulting in more serious damage of slip property.
【作者单位】：西北工业大学航海学院;西北工业大学深圳研究院;
【基金】：国家自然科学基金(51679203) 深圳市基础研究项目(JCYJ20160510140747996)资助
【分类号】：TQ021.1
【正文快照】： 引言响规律.同年,Wang等[21]提出了滑移的分子动理论(molecular kinetics)模型,并给出从无滑移到有滑移纳米流动系统因其高效、经济等优势在医学、的临界剪切率对固液相互作用强度的指数依赖关系.制药、国防以及环境监测等领域具有广泛的应用前上述研究主要集中于均质壁面上纳

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