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液滴润湿固体表面的移动接触线:从吸附到滑动

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力学学报 2024年第8期56卷 2203-2211页

作者：丁怡王意乐孙莉杰靳亚康陈龙泉电子科技大学物理学院成都611731 成都大学电子信息与电气工程学院成都610106

液滴润湿固体表面是自然界和日常生产、生活中常见的流体力学现象.针对液滴润湿固体表面过程中移动接触线的运动模式,有必要开展深入的物理力学研究.采用分子动力学模拟方法,研究了3种不同润湿性固体表面上水滴浸润的动力学过程,展示了... 详细信息

液滴润湿固体表面是自然界和日常生产、生活中常见的流体力学现象.针对液滴润湿固体表面过程中移动接触线的运动模式,有必要开展深入的物理力学研究.采用分子动力学模拟方法,研究了3种不同润湿性固体表面上水滴浸润的动力学过程,展示了全时域液滴铺展动力学行为及其相应的移动接触线标度律,并划定了液滴润湿过程的4个阶段.第1阶段中(t/τ_(i)≤0.05,其中τi为惯性-毛细特征时间),液滴与固体表面实现点接触,接触角为180°.第2阶段中(0.05﹤τ_(i)≤1),液滴动态接触角快速减小,接触半径随时间以1/2幂律关系快速增长,且不受表面润湿性的影响.第3阶段中(1﹤τ_(i)≤3),液滴动态接触角继续减小,接触半径持续增长,表面亲水性越强浸润速率越快;最后进入长期弛豫阶段(t/τ_(i)> 3),疏水表面上的液滴铺展基本结束,接触半径和接触角均趋于定值,而亲水表面上液滴动态接触角的减小明显减缓,接触半径呈指数增长.进一步标定了固-液-气三相接触线的尺寸,通过深入分析位于固-液-气三相接触线处水分子在相空间中的运动轨迹,发现了两类接触线运动模式:吸附和滑动.具体而言,在液滴润湿固体表面的第1和第2阶段中,接触线以吸附模式产生和增长;第3阶段中吸附和滑动模式并重.第4阶段中接触线则以滑动为主.文章揭示了液滴润湿固体表面的分子级运动细节,有助于进一步深入理解固-液界面微尺度流动.

关键词：润湿移动接触线吸附模式滑动模式分子动力学模拟

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黏弹性液滴撞击超疏水表面的反弹行为研究

力学学报 2024年第6期56卷 1552-1562页

作者：刘永洪王意乐代明璐丁怡靳亚康陈龙泉电子科技大学物理学院成都611731

水滴撞击超疏水表面后通常会发生完全反弹.大量研究表明,通过在液滴中添加少量聚合物可有效抑制水滴的撞击反弹行为.尽管该方法已被广泛应用于工农业生产中,但对黏弹性液滴撞击反弹行为的抑制机理认识仍不够全面.采用高速摄影技术,开展... 详细信息

水滴撞击超疏水表面后通常会发生完全反弹.大量研究表明,通过在液滴中添加少量聚合物可有效抑制水滴的撞击反弹行为.尽管该方法已被广泛应用于工农业生产中,但对黏弹性液滴撞击反弹行为的抑制机理认识仍不够全面.采用高速摄影技术,开展了聚氧化乙烯(PEO)水溶液液滴撞击不同微纳复合结构超疏水表面的实验研究.研究结果表明:添加高分子可增强流体的黏弹性及其与表面的黏附作用,因而完全反弹行为仅发生在低PEO浓度液滴的撞击实验中,且随着超疏水表面微结构间距的增大,发生完全反弹的上限和下限韦伯数阈值均减小.在低韦伯数反弹区域,撞击液滴始终处在微结构顶部,因而接触时间随韦伯数的增加而减小,这与平整超疏水表面上的现象相似;在高韦伯数反弹区域,液体会部分浸润微结构表面,因而接触时间将随韦伯数的增加而增加.此外,所有反弹液滴的恢复系数随韦伯数的增加呈线性下降趋势,且下降速率随微结构间距的增大而减缓.基于界面力学和能量转换分析,对实验中观测到的黏弹性液滴撞击反弹动力学行为给予了定性解释.

关键词：超疏水表面黏弹性液滴撞击反弹表面润湿性非牛顿流体

A cell retrievable strategy for harvesting extracellular matrix as active biointerface

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Journal of Materials Science & Technology 2022年第35期130卷 44-52页

作者： Xiangyu Dong Shuxiang Zhang Yi Xu longquan chen Qiang Wei Changsheng Zhao College of Polymer Science and Engineering State Key Laboratory of Polymer Materials and EngineeringSichuan UniversityChengdu 610065China School of Physics University of Electronic Science and Technology of ChinaChengdu 610054China College of Biomedical Engineering Sichuan UniversityChengdu 610065China State Key Laboratory of Molecular Engineering of Polymers Fudan UniversityShanghai 200433China

Extracellular matrix(ECM) provides a variety of physical and chemical cues for cells. Here, a very simple and smart method is developed to glue living cells away for harvesting their ECMs. The obtained ECM coatings show less cell fragment residues comparing with those obtained by the traditional cell lysis. The glued cell sheets can even be re-cultured and reused after transferring to new environment. This moderate way well maintains the activity of the ECM proteins, which can promote cell adhesion and ***, the ECM coatings acquired from different functional cells can guide stem cell differentiation,which is attributed to the natural physical and biochemical cues on ECM coatings. Consequently, this method provides a substantial progress for preparing natural ECM coatings and shows promising potential in regenerative medicine and other related fields of biomedical engineering.

关键词： Extracellular matrix Regenerative medicine Biocoatings Cell sheets Differentiation

Identification of surface nanobubbles and resolving their size-dependent stiffness

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Science China(Physics,Mechanics & Astronomy) 2020年第9期63卷 66-76页

作者： YouQuan Jia BinYu Zhao Abbasali Abouei Mehrizi Chuan Wang Yi Xu longquan chen School of Mechanics and Engineering Southwest Jiaotong UniversityChengdu 610031China School of Physics University of Electronic Science and Technology of ChinaChengdu 610054China Leibniz Institute of Polymer Research Dresden Dresden 01069Germany

We report a comparative investigation of the topographic features and nanomechanical responses of surface nanobubbles,polymeric nanodrops,and solid microparticles submerged in water and probed by atomic force microscopy in different operating *** show that these microscopic objects exhibit similar topographies,either hemispherical or hemiellipsoidal,in the standard tapping mode,and thus are difficult to ***,distinct differences,caused not only by their different mechanical properties but also by different cantilever tip-sample mechanical interactions that are affected by tip wettability,were observed in successive topographic imaging with controlled scanning forces and the nanoindentation tests,allowing for the identification of surface *** on the indentation force-distance curves,we further extrapolated the stiffness of surface nanobubbles spanning a wide range of sizes and then developed a simple theoretical model to explain this size *** also demonstrate how size-dependent stiffness can be used to determine the surface tension of nanobubbles,which was found to be much lower than the bulk value of water.

关键词： surface nanobubble size-dependent stiffness nanomechanical measurement atomic force microscopy

大气边界层参数化方案在核电厂址扩散参数计算中的应用研究

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环境科学与管理 2024年第7期49卷 76-81页

作者：赵多新黄莎吕明华陈龙泉中国辐射防护研究院山西太原030006

在核电厂环境污染影响评价、环境质量管理、应急等工作中,需对核电厂排放的放射性污染物在大气中迁移扩散特征进行评价,而扩散参数是核电厂环评、设计、应急相关评价软件中重要的参数。由边界层参数化方案计算扩散参数的方法应用较为普... 详细信息

在核电厂环境污染影响评价、环境质量管理、应急等工作中,需对核电厂排放的放射性污染物在大气中迁移扩散特征进行评价,而扩散参数是核电厂环评、设计、应急相关评价软件中重要的参数。由边界层参数化方案计算扩散参数的方法应用较为普遍,文章对两种常用大气边界层参数化方案在核电厂址扩散参数计算中的效果进行了讨论。与核电厂址湍流观测数据的比较显示:Mellor-Yamada 2层方案模拟结果具有较好的相关性,但方差更大;Hanna方案模拟结果相关性相对较弱,但其方差也较小,在应用中可根据两种方案各自的特点选用具体的扩散参数计算方案。

关键词：核电厂址大气边界层参数化方案扩散参数

Salvinia-like slippery surface with stable and mobile water/air contact line

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National Science Review 2021年第5期8卷 119-129页

作者： Xiaomei Li Jinlong Yang Kaixuan Lv Periklis Papadopoulos Jing Sun Dehui Wang Yanhua Zhao longquan chen Dapeng Wang Zuankai Wang Xu Deng Institute of Fundamental and Frontier Sciences University of Electronic Science and Technology of China State Key Laboratory of Polymer Physics and Chemistry Institute of Applied ChemistryChinese Academy of Sciences Physics Department University of Ioannina University Research Center of Ioannina (URCI) Institute of Materials Science and Computing Department of Mechanical Engineering City University of Hong Kong School of Physics University of Electronic Science and Technology of China

Superhydrophobic surfaces are widely used in many industrial settings, and mainly consist of rough solid protrusions that entrap air to minimize the liquid/solid area. The stability of the superhydrophobic state favors relatively small spacing between protrusions. However, this in turn increases the lateral adhesion force that retards the mobility of drops. Here we propose a novel approach that optimizes both properties simultaneously. Inspired by the hydrophobic leaves of Salvinia molesta and the slippery Nepenthes pitcher plants, we designed a Salvinia-like slippery surface(SSS) consisting of protrusions with slippery heads. We demonstrate that compared to a control surface, the SSS exhibits increased stability against pressure and impact, and enhanced lateral mobility of water drops as well as reduced hydrodynamic drag. We also systematically investigate the wetting dynamics on the SSS. With its easy fabrication and enhanced performance, we envision that SSS will be useful in a variety of fields in industry.

关键词： slippery Cassie state Salvinia molesta stability low adhesion drag reduction

Bouncing dynamics of impinging water droplets on superhydrophobic surfaces

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Bouncing dynamics of impinging water droplets on superhydrop...

Impinging water sprays on superhydrophobic meshes

中国力学大会-2021+1

作者： Yile Wang longquan chen School of Physics University of Electronic Science and Technology of China

Introduction/Highlight In this work,we carry out an experimental investigation on the bouncing behaviors of impinging water droplets on macroscopically flat superhydrophobic *** show that the restitution coefficient,which quantifies the energy consumption during impact and rebound,exhibits a non-monotonic dependence on the Weber *** is the droplet-surface friction that restricts the rebound height of the impinging droplet and thereby its restitution coefficient increases with increasing the Weber number when the impact velocity is lower than a critical value,above which theviscous friction within a thin liquid layer close to the superhydrophobic surface becomes dominant,

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Impinging water sprays on superhydrophobic meshes

Mining Land Damage Assessment and Analysis Based on ArcGIS

中国力学大会-2021+1

作者： Lijie Sun longquan chen School of Physics University of Electronic Science and Technology of China

Introduction In this work,we experimentally investigate the atomization phenomena occurring in the recoiling and spreading stages of impinging water droplets on superhydrophobic *** show that the recoiling spray is stimulated by the air cavity collapse,which is longitudinally symmetric and only happens on sufficiently hydrophobic and smooth substrates,and thus the size of the spray area on the mesh is almost identical to that of the simultaneously produced upward *** contra st,the spreading spray is expelled under the action of the inertia-induced hydrodynamic pressure,and the size of spray area on the mesh exhibits a power-law dependence on the Weber numbe r,yet the pore geometry restricts it to take a constant value when the Weber number exceeds a critical *** performing statistical analyses on the spray droplet sizes,we further demonstrate that the mean sizes of spray droplets are mainly set by the mesh pore sizes,but the complex atomization dynamics leads to a broad size distribution,which is beyond the expectation.

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Mining Land Damage Assessment and Analysis Based on ArcGIS