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On the collision of a droplet with a solid surface
Sanjeev Chandra,C.T. Avedisian +1 more
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In this paper, the collision dynamics of a liquid droplet on a solid metallic surface were studied using a flash photographic method, which provided clear images of the droplet structure during the deformation process.Abstract:
The collision dynamics of a liquid droplet on a solid metallic surface were studied using a flash photographic method. The intent was to provide clear images of the droplet structure during the deformation process. The ambient pressure (0.101 MPa), surface material (polished stainless steel), initial droplet diameter (about 1.5 mm), liquid (n-heptane) and impact Weber number (43) were fixed. The primary parameter was the surface temperature, which ranged from 24 degrees C to above the Leidenfrost temperature of the liquid. Experiments were also performed on a droplet impacting a surface on which there existed a liquid film created by deposition of a prior droplet. The evolution of wetted area and spreading rate, both of a droplet on a stainless steel surface and of a droplet spreading over a thin liquid film, were found to be independent of surface temperature during the early period of impact. This result was attributed to negligible surface tension and viscous effects, and in consequence the measurements made during the early period of the impact process were in good agreement with previously published analyses which neglected these effects. A single bubble was observed to form within the droplet during impact at low temperatures. As surface temperature was increased the population of bubbles within the droplet also increased because of progressive activation of nucleation sites on the stainless steel surface. At surface temperatures near to the boiling point of heptane, a spoke-like cellular structure in the liquid was created during the spreading process by coalescence of a ring of bubbles that had formed within the droplet. At higher temperatures, but below the Leidenfrost point, numerous bubbles appeared within the droplet, yet the overall droplet shape, particularly in the early stages of impact (< 0.8 ms), was unaffected by the presence of these bubbles. The maximum value of the diameter of liquid which spreads on the surface is shown to agree with predictions from a simplified model.read more
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Review of superoleophobic surfaces: Evaluation, fabrication methods, and industrial applications
TL;DR: In this article, the existence of superoleophobicity in nature both on plants and animals, the fundamental requirements for the fabrication of super-oleophobic surfaces, the basic and advance oleophobicity and super-ophobicity evaluation methods and also various approaches for superoleophobic surface fabrication such as sol-gel, etching, lithography, electrodeposition of conductive polymers, electrospinning, layer by layer assembly, solution-immersion, hydrothermal, anodizing, and spray coating were reviewed.
Journal ArticleDOI
A predictive model for the evolution of the thermal conductance at the casting–die interfaces in high pressure die casting
TL;DR: In this article, an analytical model is proposed to predict the time varying thermal conductance at the casting-die interface during solidification of light alloys during high pressure die casting, where the topography of the interface between the casting and the die is included in the model through the inclusion of solid surface roughness parameters and the mean trapped air layer at the interface.
Journal ArticleDOI
Influence of substrate surface conditions on the deposition and spreading of molten droplets
TL;DR: In this paper, the role of substrate surface chemistry on the interaction between the molten droplets (splats) and solid substrates in thermal spray coating was investigated. But the results were limited to a single application.
Journal ArticleDOI
Fast-freezing kinetics inside a droplet impacting on a cold surface.
Pallav Kant,Robin B. J. Koldeweij,Robin B. J. Koldeweij,Kirsten Harth,Michiel A. J. van Limbeek,Michiel A. J. van Limbeek,Detlef Lohse,Detlef Lohse +7 more
TL;DR: This work elucidate the freezing kinetics during the solidification of a droplet while it impacts on an undercooled surface and reveals and rationalizes a peculiar freezing morphology originating from the complex interplay between the droplet-scale hydrodynamics and phase-transition effects at sufficiently high substrate undercooling.
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Bubble entrapment during sphere impact onto quiescent liquid surfaces
TL;DR: In this paper, the authors report observations of air bubble entrapment when a solid sphere impacts a quiescent liquid surface, and show that a small amount of air is entrapped at the bottom tip of the impacting sphere.
References
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Surface Tension as the Cause of Bénard Cells and Surface Deformation in a Liquid Film
TL;DR: Benard as mentioned in this paper observed a cellular deformation produced on the free surface of a liquid film the bottom surface of which (in contact with a floor) was uniformly heated and hotter than its top surface.
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The Homogeneous Nucleation Limits of Liquids
TL;DR: In this article, a critical compilation of the homogeneous nucleation limits of liquids is provided, where data for 90 pure substances and 28 mixtures have been compiled over a range of pressures, nucleation rates, and compositions.
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