發(fā)布時間：2018-01-30 21:02

  本文關(guān)鍵詞： 疏液表面 親液雜質(zhì) 滑移 分子動力學(xué)　出處：《力學(xué)學(xué)報》2017年04期 　論文類型：期刊論文

【摘要】：納米流動系統(tǒng)具有高效、經(jīng)濟等優(yōu)勢,在眾多領(lǐng)域具有廣泛的應(yīng)用前景.因該類系統(tǒng)具有極高的表面積體積比,致使界面滑移效應(yīng)對流動具有顯著影響.論文采用非平衡分子動力學(xué)模擬方法,研究了疏液壁面表層混入少量親液原子時納米通道內(nèi)液體的滑移特性,并基于分子動理論解釋了其影響機制.研究發(fā)現(xiàn),親液雜質(zhì)(均布或集中)對液體法向密度振蕩程度影響較弱,但會顯著改變壁面附近類固體層的分布和液體滑移規(guī)律;隨親液雜質(zhì)占比增加,液體類固體現(xiàn)象更趨明顯,壁面處液體接觸密度也線性增大,但通道內(nèi)液體平均速度逐漸降低,滑移長度也迅速減小;相比于集中的親液雜質(zhì),均勻分布親液雜質(zhì)對滑移的弱化效應(yīng)更強.如當(dāng)親液雜質(zhì)占比為28%時,其滑移長度比單純疏液表面的降低率從50%擴大至56%.基于分子動理論的分析發(fā)現(xiàn),親液雜質(zhì)會導(dǎo)致雜質(zhì)原子附近第一液體層內(nèi)的原子發(fā)生躍遷的能壘加大,即弱化了液體原子的流向躍遷行為,從而降低了滑移量;相比于集中雜質(zhì),均勻分布的雜質(zhì)還會降低固液間的非公度性,致使滑移特性破壞更嚴重.
[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.
【作者單位】： 西北工業(yè)大學(xué)航海學(xué)院;西北工業(yè)大學(xué)深圳研究院;
【基金】：國家自然科學(xué)基金(51679203) 深圳市基礎(chǔ)研究項目(JCYJ20160510140747996)資助
【分類號】：TQ021.1
【正文快照】： 引言響規(guī)律.同年,Wang等[21]提出了滑移的分子動理論(molecular kinetics)模型,并給出從無滑移到有滑移納米流動系統(tǒng)因其高效、經(jīng)濟等優(yōu)勢在醫(yī)學(xué)、的臨界剪切率對固液相互作用強度的指數(shù)依賴關(guān)系.制藥、國防以及環(huán)境監(jiān)測等領(lǐng)域具有廣泛的應(yīng)用前上述研究主要集中于均質(zhì)壁面上納

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