Creation of prompt and thin-sheet splashing by varying surface roughness or increasing air pressure.
TL;DR: Using high-speed imaging, it is shown that surface roughness and air pressure influence both mechanisms of thin-sheet formation and ejection, and that if the air pressure is lowered, droplet ejection is suppressed not only during thin- sheet formation but also for prompt splashing.
Abstract: A liquid drop impacting a solid surface may splash either by emitting a thin liquid sheet that subsequently breaks apart or by promptly ejecting droplets from the advancing liquid-solid contact line. Using high-speed imaging, we show that surface roughness and air pressure influence both mechanisms. Roughness inhibits thin-sheet formation even though it also increases prompt splashing at the advancing contact line. If the air pressure is lowered, droplet ejection is suppressed not only during thin-sheet formation but also for prompt splashing.
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TL;DR: In this article, the authors focus on recent experimental and theoretical studies, which aim at unraveling the underlying physics, characterized by the delicate interplay of liquid inertia, viscosity, and surface tension, but also the surrounding gas.
Abstract: A drop hitting a solid surface can deposit, bounce, or splash. Splashing arises from the breakup of a fine liquid sheet that is ejected radially along the substrate. Bouncing and deposition depend crucially on the wetting properties of the substrate. In this review, we focus on recent experimental and theoretical studies, which aim at unraveling the underlying physics, characterized by the delicate interplay of not only liquid inertia, viscosity, and surface tension, but also the surrounding gas. The gas cushions the initial contact; it is entrapped in a central microbubble on the substrate; and it promotes the so-called corona splash, by lifting the lamella away from the solid. Particular attention is paid to the influence of surface roughness, natural or engineered to enhance repellency, relevant in many applications.
994 citations
Cites background from "Creation of prompt and thin-sheet s..."
...More recently, Latka et al. (2012) have proposed that perhaps www.annualreviews.org • Drop impact 13 Splashing for different viscosities....
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...Main focus is now on the levitation of the tip of the lamella, as it travels along the substrate (Latka et al. (2012); Stevens et al. (2014); Riboux and Gordillo (2014); Liu et al. (2015))....
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TL;DR: This paper reviews the recent advances in precisely controlling the printing droplets for high-resolution patterns and three-dimensional structures, with a focus on the development to suppress the coffee-ring effect and minimize the feature size of printed dots or lines.
Abstract: Inkjet printing has attracted wide attention due to the important applications in fabricating biological, optical, and electrical devices. During the inkjet printing process, the solutes prefer to deposit along the droplet periphery and form an inhomogeneous morphology, known as the coffee-ring effect. Besides, the feature size of printed dots or lines of conventional inkjet printing is usually limited to tens or even hundreds of micrometers. The above two issues greatly restrict the extensive application of printed patterns in high-performance devices. This paper reviews the recent advances in precisely controlling the printing droplets for high-resolution patterns and three-dimensional structures, with a focus on the development to suppress the coffee-ring effect and minimize the feature size of printed dots or lines. A perspective on the remaining challenges of the research is also proposed.
365 citations
TL;DR: In this paper, the mass and momentum interactions during drop impact on a liquid film are discussed in terms of underlying physical mechanisms and predictive correlations and/or models, and it is shown that much uncertainty remains, especially in regards to the interfacial features around the drop-film neck region during the earliest stages of the impact.
197 citations
TL;DR: In this paper, the impact dynamics of droplets (water, decane, ethanol, and tetradecane) onto a flat stainless steel surface, using high-speed microphotography, were investigated.
145 citations
TL;DR: In this article, the authors demonstrate that droplets can release aerosols when they influence porous surfaces, and these aerosols can deliver elements of the porous medium to the environment, revealing that knowledge of the surface properties and impact conditions can be used to predict when frenzied aerosol generation will occur.
Abstract: Aerosols are investigated because of their significant impact on the environment and human health. To date, windblown dust and sea salt from sea spray through bursting bubbles have been considered the chief mechanisms of environmental aerosol dispersion. Here we investigate aerosol generation from droplets hitting wettable porous surfaces including various classifications of soil. We demonstrate that droplets can release aerosols when they influence porous surfaces, and these aerosols can deliver elements of the porous medium to the environment. Experiments on various porous media including soil and engineering materials reveal that knowledge of the surface properties and impact conditions can be used to predict when frenzied aerosol generation will occur. This study highlights new phenomena associated with droplets on porous media that could have implications for the investigation of aerosol generation in the environment.
143 citations