Topic
Drop (liquid)
About: Drop (liquid) is a research topic. Over the lifetime, 19442 publications have been published within this topic receiving 457830 citations. The topic is also known as: metric drop.
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TL;DR: Under appropriate conditions, the coffee ring effect is able to enhance or eliminate in the authors' drying features by controlling the evaporation profile of drying drops and lines.
Abstract: We have studied inkjet-printed drops of a conductive polymer. We show how varying drop spacing and temperature lead to several different printed line morphologies and offer a simple geometric explanation for these various forms. Also, by controlling the evaporation profile of drying drops and lines, we demonstrate control of the coffee ring effect by which solute is transferred to the rim. Under appropriate conditions, we are able to enhance or eliminate the coffee ring effect in our drying features.
892 citations
TL;DR: This work measures how long the drop remains in contact with the solid during the shock to help quantify the efficiency of water-repellent surfaces (super-hydrophobic solids) and to improve water-cooling of hot solids, which is limited by the rebounding of drops as well as by temperature effects.
Abstract: When a liquid drop lands on a solid surface without wetting it, it bounces with remarkable elasticity. Here we measure how long the drop remains in contact with the solid during the shock, a problem that was considered by Hertz for a bouncing ball. Our findings could help to quantify the efficiency of water-repellent surfaces (super-hydrophobic solids) and to improve water-cooling of hot solids, which is limited by the rebounding of drops as well as by temperature effects.
888 citations
TL;DR: It is demonstrated that it is possible to reduce the contact time below this theoretical limit by using superhydrophobic surfaces with a morphology that redistributes the liquid mass and thereby alters the drop hydrodynamics.
Abstract: Surfaces designed so that drops do not adhere to them but instead bounce off have received substantial attention because of their ability to stay dry, self-clean and resist icing. A drop striking a non-wetting surface of this type will spread out to a maximum diameter and then recoil to such an extent that it completely rebounds and leaves the solid material. The amount of time that the drop is in contact with the solid--the 'contact time'--depends on the inertia and capillarity of the drop, internal dissipation and surface-liquid interactions. And because contact time controls the extent to which mass, momentum and energy are exchanged between drop and surface, it is often advantageous to minimize it. The conventional approach has been to minimize surface-liquid interactions that can lead to contact line pinning; but even in the absence of any surface interactions, drop hydrodynamics imposes a minimum contact time that was conventionally assumed to be attained with axisymmetrically spreading and recoiling drops. Here we demonstrate that it is possible to reduce the contact time below this theoretical limit by using superhydrophobic surfaces with a morphology that redistributes the liquid mass and thereby alters the drop hydrodynamics. We show theoretically and experimentally that this approach allows us to reduce the overall contact time between a bouncing drop and a surface below what was previously thought possible.
821 citations
TL;DR: In this article, the impact of a liquid drop of low viscosity on a super-hydrophobic surface was studied. But the authors focused on the effect of the drop on the spread of the liquid on the surface.
Abstract: We first study the impact of a liquid drop of low viscosity on a super-hydrophobic surface. Denoting the drop size and speed as are the liquid density and surface tension). This law is also observed to hold on partially wettable surfaces, provided that liquids of low viscosity (such as water) are used. The law is interpreted as resulting from the effective acceleration experienced by the drop during its impact. Viscous drops are also analysed, allowing us to propose a criterion for predicting if the spreading is limited by capillarity, or by viscosity.
820 citations
TL;DR: It is shown that in a coflowing stream this transition from dripping to jetting is characterized by a state diagram that depends on the capillary number of the outer fluid and the WeberNumber of the inner fluid.
Abstract: A liquid forced through an orifice into an immiscible fluid ultimately breaks into drops due to surface tension. Drop formation can occur right at the orifice in a dripping process. Alternatively, the inner fluid can form a jet, which breaks into drops further downstream. The transition from dripping to jetting is not understood for coflowing fluid streams, unlike the case of drop formation in air. We show that in a coflowing stream this transition can be characterized by a state diagram that depends on the capillary number of the outer fluid and the Weber number of the inner fluid.
808 citations