The role of drop shape in impact and splash

AbstractThe impact and splash of liquid drops on solid substrates are ubiquitous in many important fields. However, previous studies have mainly focused on spherical drops while the non-spherical situations, such as raindrops, charged drops, oscillating drops, and drops affected by electromagnetic field, remain largely unexplored. Using ferrofluid, we realize various drop shapes and illustrate the fundamental role of shape in impact and splash. Experiments show that different drop shapes produce large variations in spreading dynamics, splash onset, and splash amount. However, underlying all these variations we discover universal mechanisms across various drop shapes: the impact dynamics is governed by the superellipse model, the splash onset is triggered by the Kelvin-Helmholtz instability, and the amount of splash is determined by the energy dissipation before liquid taking off. Our study generalizes the drop impact research beyond the spherical geometry, and reveals the potential of using drop shape to control impact and splash.

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Self-Presentation and Adolescent Altruistic Behaviors in Social Networks

Complexity ◽

10.1155/2020/1719564 ◽

2020 ◽

Vol 2020 ◽

pp. 1-11

Author(s):

Yaling Zhu ◽

Yue Shen ◽

Qiang Zhao

Keyword(s):

Social Networks ◽

Opinion Formation ◽

Self Presentation ◽

Positive Prediction ◽

Network Support ◽

Social Ability ◽

Spreading Dynamics ◽

Intermediary Role ◽

The Impact

Social networks provide a convenient place for people to interact; members in social networks may create new connections or break existing connections, driving the evolution of complex network structure. Dynamics in social networks, such as opinion formation and spreading dynamics, may result in complex collective phenomena. This paper conducts a survey on 495 students from six schools in Shaanxi, Henan, and Zhejiang provinces and discusses the impact of self-presentation on adolescent network altruistic behaviors, the intermediary role of social ability cognition, and the moderating role of privacy awareness. The results show the following: (1) Self-presentation in social networks can positively predict adolescent network altruistic behaviors. The positive prediction effect of network sharing is the largest, and the positive prediction effect of network support is the least. (2) Social ability cognition plays an intermediary role between self-presentation and adolescent network altruistic behaviors. (3) The moderating effect of privacy awareness is not significant.

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Spreading dynamics of drop impacts

Journal of Fluid Mechanics ◽

10.1017/jfm.2012.431 ◽

2012 ◽

Vol 713 ◽

pp. 50-60 ◽

Cited By ~ 68

Author(s):

Guillaume Lagubeau ◽

Marco A. Fontelos ◽

Christophe Josserand ◽

Agnès Maurel ◽

Vincent Pagneux ◽

...

Keyword(s):

Dynamical Regime ◽

Viscous Effects ◽

Viscous Boundary Layer ◽

Time Resolved ◽

Drop Shape ◽

Fourier Transform Profilometry ◽

Spreading Dynamics ◽

Viscous Boundary ◽

Drop Impacts ◽

The Impact

AbstractWe present an experimental study of drop impact on a solid surface in the spreading regime with no splashing. Using the space–time-resolved Fourier transform profilometry technique, we can follow the evolution of the drop shape during the impact. We show that a self-similar dynamical regime drives the drop spreading until the growth of a viscous boundary layer from the substrate selects a residual minimal film thickness. Finally, we discuss the interplay between capillary and viscous effects in the spreading dynamics, which suggests a pertinent impact parameter.

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Exploring droplet impact near a millimetre-sized hole: comparing a closed pit with an open-ended pore

Journal of Fluid Mechanics ◽

10.1017/jfm.2015.220 ◽

2015 ◽

Vol 772 ◽

pp. 427-444 ◽

Cited By ~ 4

Author(s):

Rianne de Jong ◽

Oscar R. Enríquez ◽

Devaraj van der Meer

Keyword(s):

Impact Velocity ◽

Crucial Role ◽

Drop Impact ◽

Impact Dynamics ◽

Air Bubbles ◽

Air Bubble ◽

Impact Location ◽

Impact Phenomena ◽

The Impact

We investigate drop impact dynamics near closed pits and open-ended pores experimentally. The resulting impact phenomena differ greatly in each case. For a pit, we observe three distinct phenomena, which we denote as a splash, a jet and an air bubble, whose appearance depends on the distance between impact location and pit. Furthermore, we found that splash velocities can reach up to seven times the impact velocity. Drop impact near a pore, however, results solely in splashing. Interestingly, two distinct and disconnected splashing regimes occur, with a region of planar spreading in between. For pores, splashes are less pronounced than in the pit case. We state that, for the pit case, the presence of air inside it plays the crucial role of promoting splashing and allowing for air bubbles to appear.

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Investigations into the Role of Friction for Rigid Penetration into Concrete-Like Material Targets

Materials ◽

10.3390/ma13214733 ◽

2020 ◽

Vol 13 (21) ◽

pp. 4733

Author(s):

Ningjing Jiang ◽

Shufan Wu ◽

Yile Hu ◽

Zhongcheng Mu ◽

Xiaofeng Wu ◽

...

Keyword(s):

Experimental Data ◽

Numerical Simulations ◽

Phase Behavior ◽

Impact Dynamics ◽

Two Phase ◽

Penetration Process ◽

Simulation Results ◽

Penetration Behavior ◽

The Impact

Currently, it appears that there is a lack of understanding related to the role of SSF, in the two-phase behavior of the deceleration history, which is an issue discussed recently in the impact dynamics field. This paper analytically and numerically focuses on the effect of SSF on the projectile deceleration characteristic of concrete-like targets. Firstly, the penetration process according to the two-phase feature of the projectile deceleration is revised, where analytical results indicate that the SSF has a phased feature corresponding to the two-phase behavior of the deceleration history. Furthermore, a series of numerical simulations are conducted to understand the role of SSF more clearly. Simulation results show a similar conclusion to the analyses of the two-phase penetration process; at the range below a certain critical striking velocity, adding friction can reproduce the experimental data; when exceeding the critical striking velocity, the simulated results without considering friction are closest to the experimental data. Hence, it could be gained that the role exchange between the SSF and the dynamic term contributes to the two-phase penetration behavior for concrete-like materials. This indicates that the sensitivity of SSF to the penetration process is one of the factors driving the two-phase feature.

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Intergroup Threat and Outgroup Attitudes

Social Psychology ◽

10.1027/1864-9335/a000127 ◽

2013 ◽

Vol 44 (5) ◽

pp. 311-319 ◽

Cited By ~ 12

Author(s):

Marco Brambilla ◽

David A. Butz

Keyword(s):

Gay Men ◽

Social Group ◽

Welfare Recipients ◽

Intergroup Attitudes ◽

Social Policies ◽

Intergroup Threat ◽

Economic Threat ◽

The Impact ◽

General Climate

Two studies examined the impact of macrolevel symbolic threat on intergroup attitudes. In Study 1 (N = 71), participants exposed to a macrosymbolic threat (vs. nonsymbolic threat and neutral topic) reported less support toward social policies concerning gay men, an outgroup whose stereotypes implies a threat to values, but not toward welfare recipients, a social group whose stereotypes do not imply a threat to values. Study 2 (N = 78) showed that, whereas macrolevel symbolic threat led to less favorable attitudes toward gay men, macroeconomic threat led to less favorable attitudes toward Asians, an outgroup whose stereotypes imply an economic threat. These findings are discussed in terms of their implications for understanding the role of a general climate of threat in shaping intergroup attitudes.

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