Download or read book Water Droplet Impact Phenomena on Super hydrophobic Surface written by Patrapee Arcade and published by . This book was released on 2008 with total page 214 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Theoretical Study of Drop Impact on Structured Surfaces written by Soseh Zadoorian and published by . This book was released on 2015 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: "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." --

Download or read book Superhydrophobic Surfaces written by Russell J. Crawford and published by Elsevier. This book was released on 2015-02-19 with total page 181 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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

Download or read book Superhydrophobic Surfaces written by Mehdi Khodaei and published by . This book was released on 2020-07 with total page 132 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Droplet Impact and Solidification on Solid Surfaces in the Presence of Stagnation Air Flow written by Morteza Mohammadi and published by . This book was released on 2016 with total page 251 pages. Available in PDF, EPUB and Kindle. Book excerpt: Understanding the fundamentals of ice accretion on surfaces can help in proposing solutions to reduce or prevent ice accumulation on aircraft components and power lines. The main way in which ice forms on a surface is the solidification of supercooled droplets upon impacting on the surface. On an aircraft wing, ice accumulation can easily change the flow pattern, which could result in an increase in drag force. This research investigates the use of superhydrophobic coatings (surfaces with contact angles larger than 150) to counteract icing (anti-icing) as a result of their extremely low surface energy. The main goal of this study is to assess the performance of superhydrophobic surfaces in the presence of stagnation flow to mimic flight conditions (e.g. droplet impinging on the leading edge of an aircraft’s wing). A wide range of droplet impact velocities and stagnation flows in splashing and non-splashing regimes (at high and low Weber numbers) were carried out on surfaces with various wettabilities. The results were analyzed in order to highlight the advantages of using superhydrophobic coatings. Free stream air velocity were varied from 0 to 10 m/s with a temperature which was controlled from room temperature at 20 oC down to -30 oC. It was observed that while the presence of stagnation flow on hydrophilic (i.e. aluminum substrate) results in thin film formation for droplets with Weber numbers more than 220 upon impact in room temperature condition, instantaneous freezing at the maximum spreading diameter was observed in low temperature condition where air and substrate temperature was below the -20 oC. Same phenomenon was observed for hydrophobic substrate at aforementioned temperature. On the other hand, striking phenomenon was observed for superhydrophobic surface when stagnation air flow is present. Although it was expected droplet contact time to be increased by imposing stagnation air flow on an impacting droplet it was reduced as a function of droplet Weber number. This was referred to the presence of full slip condition rather than partial one where the spreading droplet moves on thin layer of air. Consequently, it promotes droplet ligament detachment through Kelvin-Helmholtz instability mechanism. While in low temperature condition above temperature of heterogeneous ice nucleation (i.e. -24 oC)1 supercooled water droplet contact time is reduced up to 30% to that of still air cases, droplet solidified diameter was increased up to 2 folds for air velocity up to 10 m/s compare to the still air condition at temperatures as low as -30 oC. These results were compared with a new predictive model of droplet impact behavior on the superhydrophobic substrate. New universal predictive model of droplet impact dynamics on the superhydrophobic surface was developed based on the concept of mass-spring model2 which was validated against experimental results. In the new model, viscosity effect was considered through adding a dashpot term in mass-spring model. In addition, the effect of stagnation flow was also integrated to the model through classical Homann flow approach.3 For non-isothermal condition, the effect of phase change (i.e. solidification) on droplet wetting dynamics was coupled to the model through classical nucleation theory. The universal model was compared against experimental results in room and low temperature conditions (i.e. supercooled condition) for model’s validation.

Download or read book Surfaces and Interfaces of Biomimetic Superhydrophobic Materials written by Zhiguang Guo and published by John Wiley & Sons. This book was released on 2017-09-13 with total page 402 pages. Available in PDF, EPUB and Kindle. Book excerpt: A comprehensive and systematic treatment that focuses on surfaces and interfaces phenomena inhabited in biomimetic superhydrophobic materials, offering new fundamentals and novel insights. As such, this new book covers the natural surfaces, fundamentals, fabrication methods and exciting applications of superhydrophobic materials, with particular attention paid to the smart surfaces that can show switchable and reversible water wettability under external stimuli, such as pH, temperature, light, solvents, and electric fields. It also includes recent theoretical advances of superhydrophobic surfaces with regard to the wetting process, and some promising breakthroughs to promote this theory. As a result, materials scientists, physicists, physical chemists, chemical engineers, and biochemists will benefit greatly from a deeper understanding of this topic.

Download or read book Ice Adhesion written by K. L. Mittal and published by John Wiley & Sons. This book was released on 2020-12-15 with total page 704 pages. Available in PDF, EPUB and Kindle. Book excerpt: This unique book presents ways to mitigate the disastrous effects of snow/ice accumulation and discusses the mechanisms of new coatings deicing technologies. The strategies currently used to combat ice accumulation problems involve chemical, mechanical or electrical approaches. These are expensive and labor intensive, and the use of chemicals raises serious environmental concerns. The availability of truly icephobic surfaces or coatings will be a big boon in preventing the devastating effects of ice accumulation. Currently, there is tremendous interest in harnessing nanotechnology in rendering surfaces icephobic or in devising icephobic surface materials and coatings, and all signals indicate that such interest will continue unabated in the future. As the key issue regarding icephobic materials or coatings is their durability, much effort is being spent in developing surface materials or coatings which can be effective over a long period. With the tremendous activity in this arena, there is strong hope that in the not too distant future, durable surface materials or coatings will come to fruition. This book contains 20 chapters by subject matter experts and is divided into three parts— Part 1: Fundamentals of Ice Formation and Characterization; Part 2: Ice Adhesion and Its Measurement; and Part 3: Methods to Mitigate Ice Adhesion. The topics covered include: factors influencing the formation, adhesion and friction of ice; ice nucleation on solid surfaces; physics of ice nucleation and growth on a surface; condensation frosting; defrosting properties of structured surfaces; relationship between surface free energy and ice adhesion to surfaces; metrology of ice adhesion; test methods for quantifying ice adhesion strength to surfaces; interlaboratory studies of ice adhesion strength; mechanisms of surface icing and deicing technologies; icephobicities of superhydrophobic surfaces; anti-icing using microstructured surfaces; icephobic surfaces: features and challenges; bio-inspired anti-icing surface materials; durability of anti-icing coatings; durability of icephobic coatings; bio-inspired icephobic coatings; protection from ice accretion on aircraft; and numerical modeling and its application to inflight icing.

Download or read book Wetting Hysteresis and Droplet Roll Off Behavior on Superhydrophobic Surfaces written by Katherine Marie Smyth and published by . This book was released on 2010 with total page 56 pages. Available in PDF, EPUB and Kindle. Book excerpt: Various states of hydrophobic wetting and hysteresis are observed when water droplets are deposited on micro-post surfaces of different post densities. Hysteresis is commonly defined as the difference between the advancing and receding contact angle and after many decades of research, the mechanisms governing hysteresis are still not fully understood. Particularly, stick-slip behavior of the three-phase contact line has been observed and qualitatively attributed to surface or chemical heterogeneities, but the behavior has yet to be quantified. In this thesis, contact line motion particularly focused on stick-slip behavior and its influence on drop width and contact angle was examined as a new approach to understanding hysteresis as pertaining to micro-textured surfaces. This work focuses on developing a fundamental understanding and physical model of the stick-slip behavior of the contact line and preliminarily explores the influence of contact line velocity on this stick-slip behavior and contact angle. By characterizing stick-slip behavior and hysteresis on micro-post surfaces, models can be developed that in the future can aid in surface design for optimal wetting behavior in industrial and power plant applications. Additionally, the pinning parameter has been used to predict roll off angle on micro-post surfaces for a variety of post densities and these predictions have been experimentally verified. With further definition of the pinning parameter to include surface roughness and impact phenomena, the pinning parameter can be used in surface design for droplet shedding in industrial applications.

Download or read book Collision Phenomena in Liquids and Solids written by Alexander L. Yarin and published by Cambridge University Press. This book was released on 2017-06-15 with total page 629 pages. Available in PDF, EPUB and Kindle. Book excerpt: A unique and in-depth discussion uncovering the unifying features of collision phenomena in liquids and solids, along with applications.

Download or read book Unique Phenomena of Water Drop Impact written by Arief Koeswanto and published by LAP Lambert Academic Publishing. This book was released on 2009-10-01 with total page 104 pages. Available in PDF, EPUB and Kindle. Book excerpt: Over than 200 years, the phenomena of liquid drop impact have been investigated. We can find these phenomena in our daily lives. The simple example is raindrop. We can see that a falling of liquid droplet can exhibit a variety of behaviors. From this simple intuition, the author designs a system in order to observe this phenomenon. Drop impact is a complex interaction of fluid. Generally, there are two possible outcomes of droplet impact onto a solid and dry surface, liquid droplet might deposit on the surface and form a liquid film or the droplet would splash and produce secondary droplets. With good understanding of these concepts; the author write this book to provides basic knowledge, clear investigation results of drop impact phenomena, new method to find-out the droplet size and center of mass when droplet oscillates in the air, and equations to calculate the energy dissipation which occurred before and after impact. This book will be a great foundation and useful guidance for professionals, engineers, or anyone else who have relation with petrochemicals and/or other field industries to design or optimize equipments.

Download or read book Impact and Shedding of Microdroplets on Hydrophilic and Superhydrophobic Surfaces written by Hany Gomaa and published by . This book was released on 2015 with total page 131 pages. Available in PDF, EPUB and Kindle. Book excerpt: The impact and shedding phenomena of water microdroplets on substrates with various wettabilitties are studied in this work. The analysis is aimed at illustrating the differences in behavior between micro, sub-millimeter and millimeter-sized droplets. This involved the evaluation of different parameters such as droplet maximum spreading, contact time, restitution coefficient as well as the critical air velocity for droplet shedding. The work focuses on the results obtained using a hydrophilic aluminum surface, which is the standard material used in aeronautics, and a superhydrophobic surface. After a comparative study on droplet size and surface wettability, the surface roughness effect on the impact of droplets is reported for both substrates. In addition, the adhesion of a sessile droplet on the two substrates is related to its corresponding shedding velocity. The analysis is considered a step forward in studying the behavior of cloud-sized (less than 100 æm) droplets especially on superhydrophobic surfaces. The first step of the current investigation was to design a dedicated test rig to work experimentally with microdroplets. The setup is developed to allow the microdroplet generator, camera, lighting and the designed shedding nozzle to work together without interfering with droplets imaging. Since the impact, deformation/bouncing, and shedding of the microdroplets occur in a matter of microseconds, high speed imaging is implemented. In addition, the MATLAB image processing toolbox is used to quantify the required parameters from the camera raw images by tracking their boundaries. The impact results show that the maximum spreading and recoiling of cloud-sized droplets on superhydrophobic surfaces are reduced when compared to sub-millimeter and millimeter sized droplets. This is depicted to the fact that the roughness of the superhydrophobic surface is in the same order of magnitude as the microdroplet size. Furthermore, the shedding tests illustrate that the smaller the droplet size, the higher the free stream incipient velocity needed for its shedding. The results also demonstrate the ease to remove impinged droplets from the superhydrophobic substrate when compared to the hydrophilic substrate, even at sub-zero temperatures.

Download or read book Droplet Interactions and Spray Processes written by Grazia Lamanna and published by Springer Nature. This book was released on 2020-03-14 with total page 311 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book provides a selection of contributions to the DIPSI workshop 2019 (Droplet Impact Phenomena & Spray Investigations) as well as recent progress of the Int. Research Training Group “DROPIT”.The DIPSI workshop, which is now at its thirteenth edition, represents an important opportunity to share recent knowledge on droplets and sprays in a variety of research fields and industrial applications. The research training group “DROPIT” is focused on droplet interaction technologies where microscopic effects influence strongly macroscopic behavior. This requires the inclusion of interface kinetics and/or a detailed analysis of surface microstructures. Normally, complicated technical processes cover the underlying basic mechanisms, and therefore, progress in the overall process modelling can hardly be gained. Therefore, DROPIT focuses on the underlying basic processes. This is done by investigating different spatial and/or temporal scales of the problems and by linking them through a multi-scale approach. In addition, multi-physics are required to understand e.g. problems for droplet-wall interactions, where porous structures are involved.

Download or read book Surfaces and Interfaces of Biomimetic Superhydrophobic Materials written by Zhiguang Guo and published by John Wiley & Sons. This book was released on 2017-10-10 with total page 401 pages. Available in PDF, EPUB and Kindle. Book excerpt: A comprehensive and systematic treatment that focuses on surfaces and interfaces phenomena inhabited in biomimetic superhydrophobic materials, offering new fundamentals and novel insights. As such, this new book covers the natural surfaces, fundamentals, fabrication methods and exciting applications of superhydrophobic materials, with particular attention paid to the smart surfaces that can show switchable and reversible water wettability under external stimuli, such as pH, temperature, light, solvents, and electric fields. It also includes recent theoretical advances of superhydrophobic surfaces with regard to the wetting process, and some promising breakthroughs to promote this theory. As a result, materials scientists, physicists, physical chemists, chemical engineers, and biochemists will benefit greatly from a deeper understanding of this topic.

Download or read book Condensed and Melting Droplet Behavior on Superhydrophobic Surfaces written by Fuqiang Chu and published by Springer Nature. This book was released on 2020-10-30 with total page 145 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book introduces the fabrication of superhydrophobic surfaces and some unique droplet behaviors during condensation and melting phase change on superhydrophobic surfaces, and discusses the relationship between droplet behavior and surface wettability. The contents in this book, which are all research hotspots currently, shall not only bring new insights into the physics of condensation and icing/frosting phenomena, but also provide theoretical support to solve the heat transfer deterioration, the ice/frost accretion and other related engineering problems. This book is for the majority of graduate students and researchers in related scientific areas.

Download or read book Capillarity and Wetting Phenomena written by Pierre-Gilles de Gennes and published by Springer Science & Business Media. This book was released on 2003-09-12 with total page 320 pages. Available in PDF, EPUB and Kindle. Book excerpt: The study of capillarity is in the midst of a veritable explosion. What is offered here is not a comprehensive review of the latest research but rather a compendium of principles designed for the undergraduate student and for readers interested in the physics underlying these phenomena.

Download or read book Advances in Psychology Research Volume 141 written by Alexandra M. Columbus and published by . This book was released on 2020-05-06 with total page 265 pages. Available in PDF, EPUB and Kindle. Book excerpt: Advances in Psychology Research. Volume 141 first summarizes the literature on social cognition and its neural correlates in children and adults with ADHD, focusing on emotion recognition, theory of mind, empathy, moral cognition and social decision-making.Following this, the authors explore the environmental/chemical-associated peripheral blood gene expression profiling of autism spectrum disorder, providing an explanation for the molecular mechanisms of environmental chemicals on autism spectrum disorder.A quantitative study is conducted to provide empirical evidence of the relationship between altruistic leader behavior and innovation success, using radical innovation as an explanatory variable.In addition, this compilation aims to validate a scale designed to measure authentic moral pride for children aged 10-16. Participants also completed an adaptation of the Empathy Index for Children and Adolescents.The authors go on to analyze three-year productivity data (2014-2016) from clinical psychologists assigned to U.S. Army behavioral health clinics to examine patient care productivity standards. A simple computational model compares standards from the Department of the Army, the Veterans Health Administration, and the Defense Health Agency.The influence of psychosocial and clinical factors, as well as insight, on attitude and adherence to medication in patients with psychosis is explored through a clinical case study.The services available for support and employment opportunities for individuals with serious mental illness are reviewed. Serious mental illness is defined as a diagnosable mental health disorder that "leads to serious functional impairment, which substantially interferes with or limits one or more major life activities".The closing study examines the main characteristics of a male Italian child molester, aged 50 years old, through a semi-structured interview based on the central child molester theories and possible intervention strategies

Download or read book Nanoscale and Microscale Phenomena written by Yogesh M. Joshi and published by Springer. This book was released on 2015-06-04 with total page 382 pages. Available in PDF, EPUB and Kindle. Book excerpt: The book is an outcome of research work in the areas of nanotechnology, interfacial science, nano- and micro-fluidics and manufacturing, soft matter, and transport phenomena at nano- and micro-scales. The contributing authors represent prominent research groups from Indian Institute of Technology Bombay, Indian Institute of Technology Kanpur and Indian Institute of Science, Bangalore. The book has 13 chapters and the entire work presented in the chapters is based on research carried out over past three years. The chapters are designed with number of coloured illustrations, figures and tables. The book will be highly beneficial to academicians as well as industrial professionals working in the mentioned areas.