Droplet最新文献

{"title":"Droplet impact on a wettability-patterned woven mesh","authors":"Sotiris Catsoulis,&nbsp;Uddalok Sen,&nbsp;Jens H. Walther,&nbsp;Constantine M. Megaridis","doi":"10.1002/dro2.53","DOIUrl":"https://doi.org/10.1002/dro2.53","url":null,"abstract":"<p>Droplet impact and breakup on meshes are relevant to a number of applications involving filters, textiles, and other spatially inhomogeneous media encountering gas-dispersed liquids. This study presents high-resolution simulation results of mm-size droplets striking wettability-patterned meshes with the goal of (a) replicating prior physical experiments, (b) identifying sensitivities to the initial conditions and wettability of the mesh wires, and (c) studying the fluid-field dynamics when droplets strike such meshes. The insights from the present model may help to advance understanding of droplet atomization on meshes, which depends on a number of parameters that are nontrivial to control in an experimental setting. The analysis is carried out by benchmarking the numerical methods used in a commercial software package for orthogonal droplet impact on a flat smooth surface, followed by a convergence analysis, and finally, simulation of specific experiments and case studies involving wettability-patterned mesh targets. We show that the wettability contrast between the hydrophilic and hydrophobic domains on the mesh as well as the contact angle hysteresis on each side play a critical role in determining whether liquid pinch-off occurs. The three-dimensional computational framework constructed in this work is a step toward predicting the postimpact behavior of droplets that strike woven meshes and other porous inhomogeneous media consisting of materials with different wetting properties.</p>","PeriodicalId":100381,"journal":{"name":"Droplet","volume":"2 3","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-06-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/dro2.53","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"50135383","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Droplet orthogonal impact on nonuniform wettability surfaces","authors":"Shashwata Moitra,&nbsp;Mohamed Elsharkawy,&nbsp;Antonio Russo,&nbsp;Sreya Sarkar,&nbsp;Ranjan Ganguly,&nbsp;Pietro Asinari,&nbsp;Constantine M. Megaridis","doi":"10.1002/dro2.63","DOIUrl":"https://doi.org/10.1002/dro2.63","url":null,"abstract":"<p>The vast majority of prior studies on droplet impact have focused on collisions of liquid droplets with spatially homogeneous (i.e., uniform-wettability) surfaces. But in recent years, there has been growing interest on droplet impact on nonuniform wettability surfaces, which are more relevant in practice. This paper presents first an experimental study of axisymmetric droplet impact on wettability-patterned surfaces. The experiments feature millimeter-sized water droplets impacting centrally with <math>\u0000 <semantics>\u0000 <mrow>\u0000 <mi>W</mi>\u0000 <mi>e</mi>\u0000 <mo>&lt;</mo>\u0000 <mn>100</mn>\u0000 </mrow>\u0000 <annotation> $Welt 100$</annotation>\u0000 </semantics></math> on a flat surface that has a circular region of wettability <math>\u0000 <semantics>\u0000 <mrow>\u0000 <msub>\u0000 <mi>θ</mi>\u0000 <mn>1</mn>\u0000 </msub>\u0000 </mrow>\u0000 <annotation> ${theta }_{1}$</annotation>\u0000 </semantics></math> (Area 1) surrounded by a region of wettability <math>\u0000 <semantics>\u0000 <mrow>\u0000 <msub>\u0000 <mi>θ</mi>\u0000 <mn>2</mn>\u0000 </msub>\u0000 </mrow>\u0000 <annotation> ${theta }_{2}$</annotation>\u0000 </semantics></math> (Area 2), where <math>\u0000 <semantics>\u0000 <mrow>\u0000 <msub>\u0000 <mi>θ</mi>\u0000 <mn>1</mn>\u0000 </msub>\u0000 <mo>&lt;</mo>\u0000 <msub>\u0000 <mi>θ</mi>\u0000 <mn>2</mn>\u0000 </msub>\u0000 </mrow>\u0000 <annotation> ${theta }_{1}lt {theta }_{2}$</annotation>\u0000 </semantics></math> (i.e., outer domain is less wettable than the inner one). Depending upon the droplet momentum at impact, the experiments reveal the existence of three possible regimes of axisymmetric spreading, namely (I) interior (only within Area 1) spreading, (II) contact-line entrapment at the periphery of Area 1, and (III) exterior (extending into Area 2) spreading. We present an analysis based on energetic principles for <math>\u0000 <semantics>\u0000 <mrow>\u0000 <msub>\u0000 <mi>θ</mi>\u0000 <mn>1</mn>\u0000 </msub>\u0000 <mo>&lt;</mo>\u0000 <msub>\u0000 <mi>θ</mi>\u0000 <mn>2</mn>\u0000 </msub>\u0000 </mrow>\u0000 <annotation> ${theta }_{1}lt {theta }_{2}$</annotation>\u0000 </semantics></math>, and further extend it for cases where <math>\u0000 <semantic","PeriodicalId":100381,"journal":{"name":"Droplet","volume":"2 3","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-05-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/dro2.63","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"50153749","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Hybrid electrodes effective for both electrowetting- and dielectrowetting-driven digital microfluidics","authors":"Hongyao Geng,&nbsp;Sung Kwon Cho","doi":"10.1002/dro2.58","DOIUrl":"https://doi.org/10.1002/dro2.58","url":null,"abstract":"<p>Electrowetting on dielectric (EWOD) and dielectrowetting (DEW) are two major principles to drive droplets in digital microfluidics. EWOD is effective to manipulate (create, transport, split, and merge) <i>conductive</i> droplets being currently used for many biological, chemical, and optical applications. DEW can also manipulate droplets but more efficiently with <i>dielectric</i> (nonconductive) fluids. A digital microfluidic platform efficiently operable by both EWOD and DEW would offer higher versatility in handling a wide range of fluids, regardless of their conductivities. In this regard, this article presents a new hybrid electrode design enabling EWOD and DEW to drive various kinds of droplet fluids on a single platform. In addition, a slippery liquid-infused surface (SLIPS) is integrated with the hybrid electrodes. The SLIPS is well known to resist biofouling and repel sticky fluids, which endows the hybrid electrodes with much wider application spectra. As a result, the present SLIPS-integrated hybrid electrodes facilitate actuating various kinds of fluids which would not be driven by conventional EWOD and/or DEW electrodes. This paper presents the successful transportation of not only conductive fluids including water, protein solution, glycerol, and honey but also nonconductive fluids including dodecane, silicone oil, and light and heavy crude oil, all driven by the SLIPS-integrated hybrid electrodes. The performance comparisons among solid, interdigitating, and hybrid electrodes are made by testing both conductive and nonconductive droplets.</p>","PeriodicalId":100381,"journal":{"name":"Droplet","volume":"2 3","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-05-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/dro2.58","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"50129156","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Inside Front Cover, Volume 2, Number 2, April 2023","authors":"Xiaolong Yang,&nbsp;Biao Qi,&nbsp;Yao Lu,&nbsp;Wang Zhang,&nbsp;Xiaolei Wang","doi":"10.1002/dro2.62","DOIUrl":"https://doi.org/10.1002/dro2.62","url":null,"abstract":"<p><b>Inside Front Cover</b>: The cover image is based on the Research Article <i>Bionic surface diode for droplet steering</i> by Yang et al.</p><p>Ultraslippery patterned surfaces with significant droplet sliding anisotropy were created by coordinating the heterogeneous wettability of the back of dessert beetle, directional-dependent architecture of butterfly wing, and ultraslippery configuration of Nepenthes alata. The sliding anisotropy of the functional surface is threefold higher than that of natural butterfly wings, which enables the simultaneous handling of multiple droplets without mass loss. (DOI: 10.1002/dro2.46)\u0000\u0000 <figure>\u0000 <div><picture>\u0000 <source></source></picture><p></p>\u0000 </div>\u0000 </figure></p>","PeriodicalId":100381,"journal":{"name":"Droplet","volume":"2 2","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-04-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/dro2.62","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"50136701","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Front Cover, Volume 2, Number 2, April 2023","authors":"David Van Assche,&nbsp;Thomas Beneyton,&nbsp;Jean-Christophe Baret","doi":"10.1002/dro2.59","DOIUrl":"https://doi.org/10.1002/dro2.59","url":null,"abstract":"<p><b>Front Cover</b>: The cover image is based on the Research Article <i>Rectifying jet breakup by electric forcing</i> by Van Assche et al.</p><p>Electric fields provide means to actuate droplet at high-throughput in microfluidics. Using a modulated AC-field, droplets are generated at high-throughput in a jetting regime with improved monodispersity. (DOI: 10.1002/dro2.45)\u0000\u0000 <figure>\u0000 <div><picture>\u0000 <source></source></picture><p></p>\u0000 </div>\u0000 </figure></p>","PeriodicalId":100381,"journal":{"name":"Droplet","volume":"2 2","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-04-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/dro2.59","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"50136702","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Back Cover, Volume 2, Number 2, April 2023","authors":"Youhua Jiang,&nbsp;Christian Machado,&nbsp;Kyoo-Chul K. Park","doi":"10.1002/dro2.61","DOIUrl":"https://doi.org/10.1002/dro2.61","url":null,"abstract":"<p><b>Back Cover</b>: The cover image is based on the Review Article <i>From capture to transport: A review of engineered surfaces for fog collection</i> by Jiang et al.</p><p>This cover image demonstrates that the collection of fog from an incoming fog-laden wind includes the aerodynamics-governed fog-capturing process and interfacial-phenomena-determined liquid transport process. This review introduces and discusses the definition of fog collection, fog capture process, liquid transport process, the effects of surface characteristics on fog collection performance, and the optimization of a fog collector. (DOI: 10.1002/dro2.55)\u0000\u0000 <figure>\u0000 <div><picture>\u0000 <source></source></picture><p></p>\u0000 </div>\u0000 </figure></p>","PeriodicalId":100381,"journal":{"name":"Droplet","volume":"2 2","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-04-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/dro2.61","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"50136703","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Inside Back Cover, Volume 2, Number 2, April 2023","authors":"Yi Huang,&nbsp;Shuai Yin,&nbsp;Haiwang Li,&nbsp;Sihang Liu,&nbsp;Teck Neng Wong","doi":"10.1002/dro2.60","DOIUrl":"https://doi.org/10.1002/dro2.60","url":null,"abstract":"<p><b>Inside Back Cover</b>: The cover image is based on the Research Article <i>One-step fabrication of moon-shaped microrobots through in situ solidification of magnetic Janus droplets in microchannels</i> by Huang et al.</p><p>A micro-robotic Janus particle with solid and liquid compartments has been fabricated in a one-step microfluidic process. The moon-shaped solid compartment is made up of UV-curable materials containing magnetic nanoparticles, which allows the particle to be steered by an external magnetic field, hence functioning as a micro-robot for various applications such as drug delivery and vortex generation. (DOI: 10.1002/dro2.56)\u0000\u0000 <figure>\u0000 <div><picture>\u0000 <source></source></picture><p></p>\u0000 </div>\u0000 </figure></p>","PeriodicalId":100381,"journal":{"name":"Droplet","volume":"2 2","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-04-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/dro2.60","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"50136700","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"One-step fabrication of moon-shaped microrobots through in situ solidification of magnetic Janus droplets in microchannels","authors":"Yi Huang,&nbsp;Shuai Yin,&nbsp;Haiwang Li,&nbsp;Sihang Liu,&nbsp;Teck Neng Wong","doi":"10.1002/dro2.56","DOIUrl":"https://doi.org/10.1002/dro2.56","url":null,"abstract":"<p>Special-shaped microscale structures have shed light on new possibilities in key fields of chemistry, medicine, and energy. Asymmetrical microrobots with sensitive magnetic responses can be useful tools in controlled chemical reactions, drug delivery, and functional material synthesis. Microfluidic-based emulsion generation technology is adopted as a powerful platform for the fabrication of steerable microrobots with refined control. Specifically, Janus droplets are generated in microfluidic chips featuring a flow-focusing configuration. Asymmetrical morphologies of the Janus droplets are achieved by balancing the interfacial tensions, where the portion containing magnetic nanoparticles is solidified through the UV-initiated polymerization process right after the formation while the Janus structure is left intact. We succeed in controlling the morphology of the Janus droplet along with the moon-shaped robots hydrodynamically and applying them in flow control at the microscale under external magnetic fields, which are characterized and quantified by three-dimensional profile measurement and high-speed microparticle velocimetry measurement. Our proposed on-chip fabrication method using a microfluidic platform not only provides a method for fabricating magnetic robots but also enables tuning the complex morphologies and functionalities at the microscale, which could shed light on new possibilities in key fields of controlled chemistry reaction, medicine synthesis, and energy generation.</p>","PeriodicalId":100381,"journal":{"name":"Droplet","volume":"2 2","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-04-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/dro2.56","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"50148225","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"From capture to transport: A review of engineered surfaces for fog collection","authors":"Youhua Jiang,&nbsp;Christian Machado,&nbsp;Kyoo-Chul K. Park","doi":"10.1002/dro2.55","DOIUrl":"https://doi.org/10.1002/dro2.55","url":null,"abstract":"<div>\u0000 \u0000 <p>Collecting microscale water droplets suspended in the wind, that is, fog, using permeable surfaces is a promising solution to the worldwide problem of water scarcity and is of great interest to industries, such as mist elimination and recapturing water in cooling towers. In the past few decades, this topic has attracted a drastically increasing number of researchers across a wide range of subjects. However, many aspects remain unclear, such as the definition and process of fog collection, fog collection determined from the perspectives of both the fog capture process and the liquid transport process, and how surface characteristics affect fog collection performance. In this review, we introduce and discuss fog collection from the perspectives of aerodynamics-governed fog-capturing processes and interfacial-phenomena-determined liquid transport processes. Then, an emphasis is given to the design and engineering of permeable surfaces at different length scales to optimize the fog collection performance, including the dimension, morphology, and arrangement of wires at the millimetric scale, unidirectional spreading, and Laplace pressure gradient induced by asymmetric surface geometry and nano-/microstructures. At last, a brief outlook of future research directions is provided.</p></div>","PeriodicalId":100381,"journal":{"name":"Droplet","volume":"2 2","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-04-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/dro2.55","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"50127107","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Droplet interface in additive manufacturing: From process to application","authors":"Zhengnan Sun,&nbsp;Xu Zeng,&nbsp;Xu Deng,&nbsp;Xiaosheng Zhang,&nbsp;Yi Zhang","doi":"10.1002/dro2.57","DOIUrl":"https://doi.org/10.1002/dro2.57","url":null,"abstract":"<p>Additive manufacturing (AM), which is often referred to as three-dimensional printing, revolutionizes manufacturing by providing a high degree of design freedom and customization. Several AM methods entail precise control of droplet interfacial properties to ensure the high quality of the printed products. At the same time, the rapid growth of AM technology has made it possible to prepare novel surfaces with complex structures, further expanding the range of potential applications of droplet interface. To provide a unified framework to guide the continuous development of AM that involves droplet interface, this manuscript reviews related work in this field from two aspects—the droplet interface phenomenon in AM processes and the applications of droplet interface prepared by AM. Limitations of existing works are discussed, and potential future directions are suggested.</p>","PeriodicalId":100381,"journal":{"name":"Droplet","volume":"2 2","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-04-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/dro2.57","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"50127108","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}