Condensed And Melting Droplet Behavior On Superhydrophobic Surfaces PDF Download
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| Author | : Fuqiang Chu |
| Publisher | : Springer Nature |
| Total Pages | : 145 |
| Release | : 2020-10-30 |
| Genre | : Technology & Engineering |
| ISBN | : 9811584931 |
Download Condensed and Melting Droplet Behavior on Superhydrophobic Surfaces Book in PDF, ePub and Kindle
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.
| Author | : 褚福强 |
| Publisher | : |
| Total Pages | : 0 |
| Release | : 2023 |
| Genre | : Condensation |
| ISBN | : 9787302645948 |
Download Condensed and Melting Droplet Behavior on Superhydrophobic Surfaces Book in PDF, ePub and Kindle
| Author | : Kellen Petersen |
| Publisher | : |
| Total Pages | : 189 |
| Release | : 2020 |
| Genre | : Hydrophobic surfaces |
| ISBN | : |
Download Numerical Studies of Droplets on Superhydrophobic Surfaces Book in PDF, ePub and Kindle
The work presented here explores and utilizes numerical methods to study the phenomenon of superhydrophobic surfaces. Interest in superhydrophobic surfaces has been the source of much research over the past decade due to new applications and better techniques for theoretical and computational research. Numerical simulations have been very helpful in elucidating and understanding roughness-induced superhydrophobicity and droplet behavior.In this thesis, we first explore superhydrophobic surfaces using a Gibbs free energy model. Advancing work that has been done on the metastable Cassie and Wenzel states identified by this approach, we apply the string method to identify saddle point states and associated energy barriers. Furthermore, this model is extended to include surfaces with a hierarchical microstructure that can further increase the superhydrophobicity of the surface.Next, we present and discuss a phase field model that has been used to study wetting. We then present an analysis of the shifting parameters in the model when numerically implemented and find that a near uniform shift in the phase field results in a change in the droplet size and contact angle. We also present an analysis of spontaneous droplet shrinkage and derive values for the critical droplet size in two and three dimensions such that larger droplets will not shrink.We then present results obtained using this model to study droplets on topographically and chemically patterned surfaces. We study the associated energy landscape of a pillared surface. Additionally, we discuss the different modes of transition for each surface and examine energy barrier dependence on different problem parameters.Finally, we propose a novel, proof-of-concept surface optimization problem that evolves towards an optimal surface geometry such that droplet rolling is more energetically probable than collapsing. This is achieved by minimizing an objective functional that is constructed to minimize favorable energy barriers and increase unfavorable barriers. We present a thorough development of the numerical implementation of this method and present the results from several test cases. This work introduces a new approach to the search for optimized superhydrophobic surfaces.
| Author | : Katherine Marie Smyth |
| Publisher | : |
| Total Pages | : 56 |
| Release | : 2010 |
| Genre | : |
| ISBN | : |
Download Wetting Hysteresis and Droplet Roll Off Behavior on Superhydrophobic Surfaces Book in PDF, ePub and Kindle
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.
| Author | : Deyuan Zhang |
| Publisher | : Elsevier |
| Total Pages | : 360 |
| Release | : 2021-10-28 |
| Genre | : Technology & Engineering |
| ISBN | : 0128245034 |
Download Micro- and Nano-Bionic Surfaces Book in PDF, ePub and Kindle
Micro- and Nano-Bionic Surfaces: Biomimetics, Interface Energy Field Effects, and Applications synthesizes the latest research in bio-inspired surfaces and devices for tactile and flow field perception. The book provides solutions to common problems related to flow field/tactile perception, intelligent MEMS sensors, smart materials, material removal methods, cell/particle control methods, and micro-nano robot technology. With a heavy emphasis on applications throughout, the book starts by providing insights into biomimetic device design, outlining strategies readers can adopt for various engineering applications. From there, it introduces the controlling methods of smart materials, controlling methods from external energy input, and more. Sections demonstrate how to solve problems of high efficiency, high quality, and low damage material removal for metals, composites, soft tissues, and other materials by applying bionic wave-motion surface characteristics. The latest theoretical and technical developments in field control methods applied to biological interfaces are also discussed, and the book concludes with a chapter on fabrication strategies to synthesize micro/nano functional particles based on bio-templates. Provides an overview on the latest research in bio-inspired surfaces and devices for tactile and flow-field perception Introduces techniques for characterizing different bionic surfaces and how to use energy fields analysis to treat different bionic surface and interface problems Discusses the latest theoretical and experimental developments in field control and their applications in the biomedical field Outlines fabrication methods and assembly and alignment processes of micro-/nano-functional particles based on microorganism templates
| Author | : Yifei Bian |
| Publisher | : |
| Total Pages | : |
| Release | : 2020 |
| Genre | : |
| ISBN | : |
Download Droplet Behaviour on Superhydrophobic Surfaces Book in PDF, ePub and Kindle
| Author | : David Leland Miller |
| Publisher | : |
| Total Pages | : 110 |
| Release | : 2017 |
| Genre | : |
| ISBN | : |
Download A Comparison Between Self-cleaning Properties Via Rolling Droplets and Condensation on Superhydrophobic Surfaces Book in PDF, ePub and Kindle
Superhydrophobic (SH) surfaces are super water repellent surfaces on which a droplet of water will bead up like a marble and roll off the surface with minimal tilting of the surface. This is caused by the combination of a hydrophobic coating and a rough surface structure. To achieve thermodynamic stability, surface tension of the water pulls the droplet into this shape to minimize the contact area between the droplet and the surface. This creates a high contact angle (CA) between the droplet and the surface and a low sliding angle (SA) of which the droplet begins to roll off the surface. SH surfaces have a variety of potential applications such as drag reduction, anti-icing, improved heat transfer through condensation, and self-cleaning. Numerous reports have been dedicated to exploring the fluid dynamic behavior of water droplets on SH surfaces. This thesis focuses on exploring the self-cleaning properties of SH surfaces. Surfaces contaminated with salt, tobacco, and pollen are cleaned by rolling water droplets over the surface or condensing water on the surface such that when large enough, these droplets roll away due to gravity. SH surfaces explored here are composed of micro-scale or nano-scale rib and cavity structures and and are compared with smooth, hydrophobic surfaces with a similar hydrophobic coating.
| Author | : Alain Carré |
| Publisher | : CRC Press |
| Total Pages | : 510 |
| Release | : 2009-04-24 |
| Genre | : Science |
| ISBN | : 9004165932 |
Download Superhydrophobic Surfaces Book in PDF, ePub and Kindle
Superhydrophobic surfaces (water contact angles higher than 150o) can only be achieved by a combination of hydrophobicity (low surface energy materials) with appropriate surface texture. In nature one can find an array of impressive and elegant examples of superhydrophobic surfaces. For example, on a lotus leaf rain drops bounce off after impact, then entirely roll off the lotus leaf and drag along any dirt particles, without leaving residues. The artificial design of superhydrophobic and self-cleaning surfaces has become an extremely active area of fundamental and applied research. This book presents both fundamental and applied aspects of superhydrophobic surfaces. It describes also different strategies for making superhydrophobic surfaces from a large diversity of materials (polymers, metals and other inorganic materials, composites) and processes (lithographic techniques, electrochemical processes, self-assembly processes, colloidal particles, sol-gel processes, nanofilaments, or simple scraping). A bountiful of information is covered in this book which represents cumulative wisdom of many world-renowned researchers in the fascinating and burgeoning area of superhydrophobic surfaces.
| Author | : Hany Gomaa |
| Publisher | : |
| Total Pages | : 131 |
| Release | : 2015 |
| Genre | : |
| ISBN | : |
Download Impact and Shedding of Microdroplets on Hydrophilic and Superhydrophobic Surfaces Book in PDF, ePub and Kindle
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.
| Author | : K. L. Mittal |
| Publisher | : John Wiley & Sons |
| Total Pages | : 704 |
| Release | : 2020-12-15 |
| Genre | : Technology & Engineering |
| ISBN | : 1119640377 |
Download Ice Adhesion Book in PDF, ePub and Kindle
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.
