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Wetting property of smooth and textured hydrophobic surfaces under condensation condition

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Science China(Physics,Mechanics & Astronomy) 2014年第11期57卷 2127-2132页

作者： HAO PengFei lv cunjing YAO ZhaoHui NIU FengLei Department of Engineering Mechanics Tsinghua University State Key Laboratory of Alternate Electrical Power System with Renewable Energy Sources North China Electric Power University

Static and dynamic wetting behaviors of sessile droplet on smooth,microstructured and micro/nanostructured surface under condensation condition are systematically *** contrast to the conventional droplet wetting on such natural materials by dropping,we demonstrate here that when dropwise condensation occurs,the sessile droplet will transit from the Cassie-Baxter wetting state to the Wenzel wetting state or partial Cassie-Baxter wetting state on the microstructured surface or the micro/nanostructured surface,which leads to a strong adhesion between the droplet and the *** contrast,the apparent contact angle and the sliding angle on the smooth surface changes a little before and after the condensation because of small *** analysis shows that the roughness factor controls the adhesion force of the droplet during condensation,and a theoretical model is constructed which will be helpful for us to understand the relationship between the adhesion force and the geometry of the surface.

关键词： condensation hydrophobic roughness droplet systematically wetting apparent nanotube structured diameters

Water droplet impact on superhydrophobic surfaces with microstructures and hierarchical roughness

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Science China(Physics,Mechanics & Astronomy) 2014年第7期57卷 1376-1381页

作者： HAO PengFei lv cunjing NIU FengLei YU Yu Department of Engineering Mechanics Tsinghua University State Key Laboratory of Alternate Electrical Power System with Renewable Energy Sources North China Electric Power University

Quantitative correlation between the critical impact velocity of droplet and geometry of superhydrophobic surfaces with microstructures is systematically *** data shows that the critical impact velocity induced wetting transition of droplet on the superhydrophobic surfaces is strongly determined by the perimeter of single micropillar,the space between the repeat pillars and the advancing contact angle of the sidewall of the *** proposed model agrees well with the experimental results,and clarifies that the underlying mechanism which is responsible for the superhydrophobic surface with hierarchical roughness could sustain a higher liquid pressure than the surfaces with microstructures.

关键词： impact velocity superhydrophobic advancing contact angle

Suspended penetration wetting state of droplets on microstructured surfaces

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Science China(Physics,Mechanics & Astronomy) 2021年第4期64卷 81-89页

作者： Jing Lou SongLin Shi Chen Ma cunjing lv QuanShui Zheng Department of Engineering Mechanics and Center for Nano and Micro Mechanics Tsinghua UniversityBeijing 100084China State Key Laboratory of Tribology Tsinghua UniversityBeijing 100084China

When a water droplet on a micropillar-structured hydrophobic surface is submitted to gradually increased pressure, the CassieBaxter wetting state transforms into the Wenzel wetting state once the pressure exceeds a critical value. It has been assumed that the reverse transition(Wenzel-to-Cassie-Baxter wetting state) cannot happen spontaneously after the pressure has been *** this paper, we report a new wetting-state transition. When external pressure is exerted on a droplet in the Cassie-Baxter wetting state on textured surfaces with high micropillars to trigger the breakdown of this wetting state, the droplet penetrates the micropillars but does not touch the base of the surface to trigger the occurrence of the Wenzel wetting state. We have named this state the suspended penetration wetting state. Spontaneous recovery from the suspended penetration wetting state to the initial Cassie-Baxter wetting state is achieved when the pressure is removed. Based on the experimental results, we built models to establish the penetration depth that the suspended penetration wetting state could achieve and to understand the energy barrier that influences the equilibrium position of the liquid surface. These results deepen our understanding of wetting states on rough surfaces subjected to external disturbances and shed new light on the design of superhydrophobic materials with a robust wetting stability.

关键词： wetting micropillars hydrophobic transition stability

Writing with a nano-grooved pin

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Science China(Technological Sciences) 2019年第9期62卷 1649-1654页

作者： DONG HuaLai YANG Xing lv cunjing WANG Jin ZHENG QuanShui State Key Laboratory of Precision Measurement Technology and Instruments Department of Precision InstrumentTsinghua UniversityBeijing 100084China Center for Nano and Micro Mechanics Tsinghua UniversityBeijing 100084China Department of Engineering Mechanics Tsinghua UniversityBeijing 100084China

As a basic technology, dispensing liquid into small droplets is widely used in many nowadays technologies, such as 3D printing [I-4], biological/chemical patterning [5-7], and drug discovery [8,9]. Traditional transfer methods by pipette or pin, which may date to 4000 years ago [10], are simple and cheap to generate droplets bigger than μ100 pm [11] for most materials.

关键词： technology droplets materials

Controlling the trajectories of nano-/micro particles using light/actuated Marangoni flow

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Controlling the trajectories of nano-/micro particles using ...

双材平面中环形界面环向裂纹问题的超奇异积分方程方法

第十二届全国生物力学学术会议暨第十四届全国生物流变学学术会议

作者： cunjing lv Tsinghua University

Objective The ability to manipulate small objects and to produce patterns on the nano-and microscale is very important because of fundamentals and technological applications. The manipulation of particles with diameters of the order of 100 nm or below is very challenge due to the Brownian motion, as well as the scaling behavior of methods such as optical trapping. Methods that use hydrodynamic forces to manipulate particles offer

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来源： cnki会议评论

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机械强度 2006年第5期28卷 733-738页

作者：杜云海吕存景董栋柯献辉郑州大学工程力学系郑州450001

从研究环形界面双相材料平面任点处沿径向、环向作用单位力时的弹性力学基本解出发,利用Betti定律、几何关系和虎克定律得到双材料平面环向裂纹问题的位移场和应力场表达式,经代入裂纹岸应力边界条件,导出极坐标下以裂纹岸位移间断为基... 详细信息

从研究环形界面双相材料平面任点处沿径向、环向作用单位力时的弹性力学基本解出发,利用Betti定律、几何关系和虎克定律得到双材料平面环向裂纹问题的位移场和应力场表达式,经代入裂纹岸应力边界条件,导出极坐标下以裂纹岸位移间断为基本未知量的超奇异积分方程组;通过适当的积分变换,用有限部积分原理处理方程组中所包含的两类奇异积分—Cauchy奇异积分和超奇异积分,解决极坐标下环形界面双材料平面环向裂纹问题用超奇异积分方程法的理论描述与数值算法。在嵌入物半径足够大时,计算结果与已发表文献对直线界面情况下平行于界面裂纹问题的计算结果一致。

关键词：双相材料极坐标环向裂纹超奇异积分方程应力强度因子