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drop impact on substrates with heterogeneous stiffness

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Chinese Physics B 2022年第8期31卷 479-484页

作者：成阳郑建艮杨晨袁松雷陈果刘雳宇 Chongqing Key Laboratory of Soft Condensed Matter Physics and Smart Materials College of PhysicsChongqing UniversityChongqing 400044China School of Optoelectronic Engineering Chongqing University of Posts and TelecommunicationsChongqing 400065China

Previous studies of drop impact mainly focus on homogeneous substrates while heterogeneous substrates remain largely unexplored. A convenient preparation strategy of stiff heterogeneous substrates is presented in this work, and the drop impact on such a stiffness-patterned substrate consisting of soft spirals surrounded by a rigid region is systematically investigated. The results show that the splash behavior of a drop on a stiffness-patterned substrate exhibits distinct characteristics from those on a homogeneous substrate. Prompt splash is more likely to occur on the substrate with the greater heterogeneity of stiffness, which is reflected in the lower critical impact velocity. Moreover, the splash velocity of emitted droplet is significantly larger on the heterogeneous substrate than that on a corresponding homogeneous substrate,especially at a higher impact velocity of the drop, indicating a stronger splash intensity on the heterogeneous *** difference in drop splashing between homogeneous substrate and heterogeneous substrate is largely due to the stiffness heterogeneity, rather than the variation of overall stiffness of the substrate. The use of spiral shape provides a feasible solution for introducing stiffness heterogeneity of substrate. This study is conducive to the understanding of drop impact research beyond uniform substrates, reveals the potential of using stiffness-patterned substrates to control splash, and may find useful applications in industries related to drop impact and splash.

关键词： drop impact stiffness-patterned substrate splash

A LATTICE BOLTZMANN METHOD FOR SIMULATION OF A THREE-DIMENSIONAL drop impact ON A LIQUID FILM

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Journal of Hydrodynamics 2008年第3期20卷 267-272页

作者： SHI Zi-yuan YAN Yong-hua YAN-G Fan QIAN Yue-hong HU Guo-hui Shanghai Institute of Applied Mathematics and Mechanics Shanghai University Shanghai 200072 China Shanghai Key Laboratory of Mechanics in Energy and Environment Engineering Shanghai 200072 China Shanghai East Pump （Group） Co. Ltd Shanghai 201907 China

A single-phase free surface tracking model based on the Lattice Boltzmann Method （LBM）, which has capability of simulating liquid-gas system with the assumption that the gas phase has only negligible influence on the liquid phase, is utilized to simulate the flow of a drop impacting on a liquid film. Three typical outcomes in the flows, i.e., deposition, crown and splash, which have been observed in the previous experiments, are obtained in the present three dimensional numerical simulations. The numerical results are consistent with the experimental and analytical results available.

关键词： Lattice Boltzmann Method (LBM) drop impact two-phase flows thin film

Effect of viscosity on motion of splashing crown in high speed drop impact

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Applied Mathematics and Mechanics(English Edition) 2017年第12期38卷 1709-1720页

作者： Shihao YANG Yi AN Qingquan LIU Institute of Mechanics Chinese Academy of Sciences School of Aerospace Engineering Beijing Institute of Technology

A splashing crown is commonly observed when a high-speed drop impacts a liquid film. The influence of the liquid viscosity on the crown＇s evolution is not yet clear. We review several existing theories of this problem, and carry out a series of numerical simulations. We find that a three-segment model can describe the crown＇s motion. In the very early stage when the crown is barely visible, the influence of viscosity is small. Later, a shallow water approach used in most existing models is applicable as long as the initial conditions are formulated properly. They depend on viscous dissipation in the intermediate period. Preliminary estimation based on a dissipation function is proposed to characterize the influence of viscosity in this problem.

关键词： drop impact crown viscosity coupled level-set volume of fluid (CLSVOF) method

Cavity dynamics of water drop impact onto immiscible oil pool with different viscosity

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Acta Mechanica Sinica 2021年第3期37卷 447-455,I0002页

作者： Muhammad Mohasan Anas Bin Aqeel Pengyu Lv Yantao Yang Huiling Duan SKLTCS and Department of Mechanics and Engineering Science BIC-ESATCollege of EngineeringPeking UniversityBeijing 100871China National University of Sciences and Technology H-12IslamabadPakistan Key Laboratory of High Energy Density Physics Simulation Center for Applied Physics and TechnologyPeking UniversityBeijing 100871China

In this work,we numerically study the impact of a water droplet onto a deep oil *** fluids are immiscible and the viscosity of the pool liquid is changed *** focus on the cavity dynamics during the impact and especially the effects of the pool liquid viscosity and the impacting *** the parameter range explored,we identify the regime where splashing occurs with corolla breaking into droplets,and the regime where no splashing is *** is found for the time evolution of cavity depth for fixed impact velocity and different viscosity,if the cavity depth and time are nondimensionalized by the maximal depth and the time when the maximal depth is *** power-law scalings are also proposed to describe the dependence of the maximal cavity depth and the corresponding time on the impact velocity and pool liquid viscosity,in the term of Froude and Reynolds numbers.

关键词： drop impact Immiscible fluids Cavity dynamics

Correlating solder interconnects failure with PCBs response during board level drop impact test

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China Welding 2012年第2期21卷 7-12页

作者：刘洋孙凤莲 School of Materials Science and Engineering Harbin University of Science and TechnologyHarbin150030

Solder interconnects reliability during drop impact is important for portable electronic products. In this paper, board level drop impact tests were conducted according to the standard of the Joint Electronic Devices Engineering Council （JEDEC）. Solder failure drop numbers were recorded and solder failure analyses were carried out. A high speed data acquisition system was constructed to measure the printed cireuit board （ PCt~ ） dynamic response during the impact. Measured response data were used to characterize the loading feature of the impact. The relatioT~~hip between solder failure features and PCB dynamic response was correlated. Solder failure mechanisms were discussed. The correlation of PCB strain data with the solder failure life indicates that the solder damage accumulated during drop impact is dependent on both strain amplitude and modes contribution of the PCB. Compared with high strain amplitude loading condition, lower strain amplitude with higher mode can even produce more severe damage to the solder interconnects. Repeated impact loadings to the solder induce the combination failure mechanism of both impact and fatigue. Failure analyses results provide convincing verification for the complexity of the failure mechanisms.

关键词： solder printed circuit board drop impact strain failure

Oblique drop impact on Deep and Shallow Liquid

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Communications in Computational Physics 2012年第4期11卷 1386-1396页

作者： B.Ray G.Biswas A.Sharma Department of Mechanical Engineering Indian Institute of Technology KanpurKanpur 208016India CSIR-Central Mechanical Engineering Research Institute Durgapur 713209India Department of Chemical Engineering Indian Institute of Technology KanpurKanpur 208016India

Numerical simulations using CLSVOF(coupled level set and volume of fluid)method are performed to investigate the coalescence and splashing regimes when a spherical water drop hits on the water surface with an impingement *** angle is the angle between the velocity vector of primary drop and the normal vector to water *** effect of impingement angle,impact velocity and the height of target liquid are carried *** impingement angle is varied from 0o to 90o showing the gradual change in *** formation of ship pro like shape,liquid sheet,secondary drops and crater are *** height,crater displacement,crown height and crown angle are calculated and the change in the parameters with change in impingement angle is noted.

关键词： Coupled level set and volume of fluid method drop impact impingement angle Weber number

Vorticity effects in drop impact

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Vorticity effects in drop impact

impact response and energy absorption of metallic buffer with entangled wire mesh damper

第九届全国流体力学学术会议

作者： Marie-Jean THORAVAL Sigurdur T.THORODDSEN International Center for Applied Mechanics State Key Laboratory for Strength and Vibration of Mechanical StructuresXi'an Jiaotong University Division of Physical Sciences and Engineering & Clean Combustion Research Center King Abdullah University of Science and Technology(KAUST)

The impact of drop on a liquid pool can entrap bubbles and splash smaller *** bubbles can dissolve and transfer gas into the pool,while the droplets can generate *** studies on drop impacts have neglected the effect of vorticity on the *** were able to reproduce the large scale dynamics of the drop entering the ***,recent results have demonstrated that the vorticity produced at the air-liquid interface plays a critical role in explaining the complex dynamics of splashing and air *** focus here on the dynamics of the air bubble entrapped just after contact between the drop and the *** show the role of vorticity in producing a large range of different bubble shape,including toroidal bubbles,and bubbles containing a liquid droplet

关键词： drop impact Air Entrapment Splashing Vorticity Vortex Ring

来源： cnki会议评论

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Defence Technology（防务技术） 2024年第5期35卷 137-150页

作者： Chao Zheng Jun Wu Mangong Zhang Xin Xue Institute of Metal Rubber&Vibration Noise School of Mechanical Engineering and AutomationFuzhou UniversityFuzhou 350116China Wuhan Second Ship Design and Research Institute Wuhan 430205China

An innovative metallic buffer consisting of series-connected hat-shaped entangled wire mesh damper(EWMD)and parallel springs are proposed in this work to enhance the reliability of engineering *** impact response and the energy dissipation mechanism of hat-shaped EWMD under different quasi-static compression deformations(2-7 mm)and impact heights(100-200 mm)are investigated using experimental and numerical *** results demonstrate distinct stages in the quasi-static mechanical characteristics of hat-shaped EWMD,including stiffness softening,negative stiffness,and stiffness *** loss factor gradually increases with increasing compression deformation before entering the stiffness hardening *** impact loads,the hat-shaped EWMD exhibits optimal impact energy absorption when it enters the negative stiffness stage(150 mm),resulting in the best impact isolation effect of metallic ***,the impact energy absorption significantly decreases when hat-shaped EWMD enters the stiffness hardening ***,quasi-static compression analysis after experiencing different impact loads reveals the disappearance of the negative stiffness ***,with increasing impact loads,the stiffness hardening point progressively shifts to an earlier stage.

关键词： Metallic buffer Hat-shaped EWMD drop impact Energy absorption characteristics Mechanical behavior

Jet formation during the impact of an air-liquid compound drop onto a liquid pool

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Jet formation during the impact of an air-liquid compound dr...