Theoretical Study of Drop Impact on Structured Surfaces PDF Download
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Author: Soseh Zadoorian
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Book Description
"Droplet impact on superhydrophobic surfaces has been studied extensively due to its abundance and importance in natural and industrial phenomena. As superhydrophobic surfaces may lose their superhydrophobicity due to droplet impact in many applications, the robustness of the superhydrophobic surfaces is important. The superhydrophobicity of a surface is characterized by the surface chemistry and roughness. The liquid on a rough surface forms a liquid-air interface due to the existence of air inside the surface cavities. To have a robust superhydrophobic surface, the liquid should not wet the entire surface cavities, but only the top of surface asperities. Thus, the liquid will be supported by a liquid-solid and a liquid-air interface. Liquid penetration into the air cavities will lead to an irreversible transition. To prevent this wetting transition, a design criterion for regularly patterned rough surfaces is established based on a pressure balance on the liquid-air interface. The effective pressure terms on the liquid-air interface for an impacting droplet condition are introduced first. To avoid liquid penetration, the wetting pressure, which is the Water-hammer pressure, must be smaller than the non-wetting pressure, which is the Laplace pressure. In this work, these two pressure terms are modified for rough structured surfaces. The Water-hammer pressure for structured surfaces is derived based on two different approaches, the impacting droplet model and the electrical circuit model. According to the derived equation for the Water-hammer pressure on structured surfaces, a correlation for the water-hammer coefficient is introduced for structured surfaces. The Laplace pressure on structured surfaces is modified based on two simplifying assumptions for the shape of the liquid-air interface. A spherical cap shape is assumed for the liquid-air interface and a sagging wetting transition mechanism is considered.It is shown that both pressure terms can be derived as a function of surface structures. Thus the pressure balance results in a design criterion for the surface structures. In addition to the pressure balance, another design criterion is presented based on the limiting penetration depth for the liquid-air interface inside the surface cavities at the moment of impact." --
Author: Soseh Zadoorian
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Book Description
"Droplet impact on superhydrophobic surfaces has been studied extensively due to its abundance and importance in natural and industrial phenomena. As superhydrophobic surfaces may lose their superhydrophobicity due to droplet impact in many applications, the robustness of the superhydrophobic surfaces is important. The superhydrophobicity of a surface is characterized by the surface chemistry and roughness. The liquid on a rough surface forms a liquid-air interface due to the existence of air inside the surface cavities. To have a robust superhydrophobic surface, the liquid should not wet the entire surface cavities, but only the top of surface asperities. Thus, the liquid will be supported by a liquid-solid and a liquid-air interface. Liquid penetration into the air cavities will lead to an irreversible transition. To prevent this wetting transition, a design criterion for regularly patterned rough surfaces is established based on a pressure balance on the liquid-air interface. The effective pressure terms on the liquid-air interface for an impacting droplet condition are introduced first. To avoid liquid penetration, the wetting pressure, which is the Water-hammer pressure, must be smaller than the non-wetting pressure, which is the Laplace pressure. In this work, these two pressure terms are modified for rough structured surfaces. The Water-hammer pressure for structured surfaces is derived based on two different approaches, the impacting droplet model and the electrical circuit model. According to the derived equation for the Water-hammer pressure on structured surfaces, a correlation for the water-hammer coefficient is introduced for structured surfaces. The Laplace pressure on structured surfaces is modified based on two simplifying assumptions for the shape of the liquid-air interface. A spherical cap shape is assumed for the liquid-air interface and a sagging wetting transition mechanism is considered.It is shown that both pressure terms can be derived as a function of surface structures. Thus the pressure balance results in a design criterion for the surface structures. In addition to the pressure balance, another design criterion is presented based on the limiting penetration depth for the liquid-air interface inside the surface cavities at the moment of impact." --
Author: Matheu Alec James Broom
Publisher:
ISBN:
Category : Drops
Languages : en
Pages : 266
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Book Description
This Thesis describes the study of water drop impacts on microstructured surfaces. Previous studies of liquid droplets impacting on solid surfaces have mostly been concerned with smooth flat surfaces. The introduction of an array of micrometre-scale pillars (microstructure) adds new research avenues. This work systematically studies the effect of the microstructure design on droplet impact phenomena. The experiments in this study include over 800 high speed videos of water drop impacts on 23 different surface designs. Droplets with an average diameter D0 = 2.51 ± 0.04 mm are produced with 11 discrete impact velocities in the range of 1.5 - 2.5 m/s producing a range of impact Weber numbers (We) from 50 to 250. Soft-lithography methods are used for the production of polydimethylsiloxane (PDMS) surfaces. The microstructures consist of 20 μm width pillars of both circular and square cross sectional shape arranged in square arrays. A selection of pillar spacings (40 μm, 60 μm and 80 μm) and pillar heights (15 μm, 22 μm and 30 μm) is investigated. The creation of a dual view time-synchronized high-speed imaging system is demonstrated. Using this system, drop impact events can be recorded at frame rates between 10,000 and 42,000 frames per second (fps), with an exposure time between 10 μs and 2 μs. High magnification optics produce a spatial resolution range of ± 20 μm to ± 4 μm. A Matlab image processing script is created for the automatic extraction of data during real time (25 fps) playback. These methods are first employed to study phenomena that are observed promptly after the impact event (
Author: Šefko Šikalo
Publisher:
ISBN: 9783832214661
Category :
Languages : en
Pages : 144
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Book Description
Author: Ross D. Brazee
Publisher:
ISBN:
Category : Drops
Languages : en
Pages : 8
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Book Description
Author: Martin Rein
Publisher: Springer
ISBN: 3709125944
Category : Technology & Engineering
Languages : en
Pages : 317
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Book Description
This book presents a comprehensive overview of fluid mechanical, thermal and physico-chemical aspects of drop-surface interactions. Basic physical mechanisms pertaining to free-surface flow phenomena characteristic of drop impact on solid and liquid surfaces are explained emphasizing the importance of scaling. Moreover, physico-chemical fundamentals relating to a forced spreading of complex solutions, analytical tools for calculating compressibility effects, and heat transfer and phase change phenomena occurring during solidification and evaporation processes, respectively, are introduced in detail. Finally, numerical approaches particularly suited for modeling drop-surface interactions are consisely surveyed with a particular emphasis on boundary integral methods and Navier-Stokes algorithms (volume of fluid, level set and front tracking algorithms). The book is closed by contributions to a workshop on Drop-Surface Interactions held at the International Centre of Mechanical Sciences.
Author: Russell J. Crawford
Publisher: Elsevier
ISBN: 0128013311
Category : Technology & Engineering
Languages : en
Pages : 181
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Book Description
Superhydrophobic Surfaces analyzes the fundamental concepts of superhydrophobicity and gives insight into the design of superhydrophobic surfaces. The book serves as a reference for the manufacturing of materials with superior water-repellency, self-cleaning, anti-icing and corrosion resistance. It thoroughly discusses many types of hydrophobic surfaces such as natural superhydrophobic surfaces, superhydrophobic polymers, metallic superhydrophobic surfaces, biological interfaces, and advanced/hybrid superhydrophobic surfaces. - Provides an adequate blend of complex engineering concepts with in-depth explanations of biological principles guiding the advancement of these technologies - Describes complex ideas in simple scientific language, avoiding overcomplicated equations and discipline-specific jargon - Includes practical information for manufacturing superhydrophobic surfaces - Written by experts with complementary skills and diverse scientific backgrounds in engineering, microbiology and surface sciences
Author: Alexander L. Yarin
Publisher: Cambridge University Press
ISBN: 1107147905
Category : Science
Languages : en
Pages : 629
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Book Description
A unique and in-depth discussion uncovering the unifying features of collision phenomena in liquids and solids, along with applications.
Author: Marco Marengo
Publisher: Springer Nature
ISBN: 3030829928
Category : Science
Languages : en
Pages : 390
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Book Description
The Surface Wettability Effect on Phase Change collects high level contributions from internationally recognised scientists in the field. It thoroughly explores surface wettability, with topics spanning from the physics of phase change, physics of nucleation, mesoscale modeling, analysis of phenomena such drop evaporation, boiling, local heat flux at triple line, Leidenfrost, dropwise condensation, heat transfer enhancement, freezing, icing. All the topics are treated by discussing experimental results, mathematical modeling and numerical simulations. In particular, the numerical methods look at direct numerical simulations in the framework of VOF simulations, phase-field simulations and molecular dynamics. An introduction to equilibrium and non-equilibrium thermodynamics of phase change, wetting phenomena, liquid interfaces, numerical simulation of wetting phenomena and phase change is offered for readers who are less familiar in the field. This book will be of interest to researchers, academics, engineers, and postgraduate students working in the area of thermofluids, thermal management, and surface technology.
Author: Martin Rein
Publisher: Springer Science & Business Media
ISBN: 9783211836927
Category : Computers
Languages : en
Pages : 328
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Book Description
This book presents a comprehensive overview of fluid mechanical, thermal and physico-chemical aspects of drop-surface interactions. Basic physical mechanisms pertaining to free-surface flow phenomena characteristic of drop impact on solid and liquid surfaces are explained emphasizing the importance of scaling. Moreover, physico-chemical fundamentals relating to a forced spreading of complex solutions, analytical tools for calculating compressibility effects, and heat transfer and phase change phenomena occurring during solidification and evaporation processes, respectively, are introduced in detail. Finally, numerical approaches particularly suited for modeling drop-surface interactions are consisely surveyed with a particular emphasis on boundary integral methods and Navier-Stokes algorithms (volume of fluid, level set and front tracking algorithms). The book is closed by contributions to a workshop on Drop-Surface Interactions held at the International Centre of Mechanical Sciences.
Author: Salman Buksh Sookran
Publisher:
ISBN:
Category :
Languages : en
Pages : 0
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Book Description
This thesis has made progress in two different areas related to drop impact onto a surface. Firstly, a systematic experimental study has been performed to understand asymmetric spreading of low and high surface tension liquids on a moving surface. A new time evolution model for droplet spreading on a moving surface was developed. This model regardless the value of surface tension of the liquid can predict the spreading of low viscous (1-4cSt) liquids on a moving surface. Secondly, liquids with viscosity (1-5cSt) and surface tension (17.4-72.8mNm) were used to study the drop impact on moving and inclined surface. Experiments performed with similar normal (0.9-2.9m/s) and tangential (0.8-2.9m/s) velocities on both surfaces to test our hypothesis that spreading/splashing for these two surface conditions should be same. Results indicates that our hypothesis is true, except for some special conditions when, normal and tangential velocities are greater than the range of our analysis.
