Kui He, Zhiling Zhang, Liangzhen Zhang, Wuzhi Yuan, Si-Min Huang
{"title":"Effects of geometrical confinement on the generation of droplets at microfluidics T-junctions with rectangle channels","authors":"Kui He, Zhiling Zhang, Liangzhen Zhang, Wuzhi Yuan, Si-Min Huang","doi":"10.1007/s10404-023-02678-9","DOIUrl":null,"url":null,"abstract":"<div><p>Despite the fact that there are not a few relative studies, the effects of geometrical confinement on droplets’ generation at micro-T-junctions are not explicitly addressed. A three-dimensional volume of fluid (VOF) CFD model is developed here to study this classic microfluidics problem. The micro-T-junctions are designed with arms of a same hydraulic diameter but different width-to-depth ratios (<span>\\(\\chi \\)</span> = 1/10–10), covering both deep-style (<span>\\(\\chi <1)\\)</span> and flat-style T-junctions (<span>\\(\\chi >1)\\)</span>. It is found that the width-to-depth ratio (confinement style) shows complex effects on the dynamics of droplets’ generation. At <span>\\(\\chi \\le 1/10\\)</span>, droplets are failed to be generated at the T-junctions. Compared to the normal T-junctions (<span>\\(\\chi >1\\)</span>), the deep-style T-junctions (<span>\\(1/6<\\chi <\\)</span> 1) show much higher generation frequency of droplets at <span>\\({\\mathrm{Ca}}_{\\mathrm{c}}>0.06\\)</span> and the volume of generated droplets scales with <span>\\({{\\mathrm{Ca}}_{\\mathrm{c}}}^{-1}\\)</span> instead of typical <span>\\({{\\mathrm{Ca}}_{\\mathrm{c}}}^{-0.33}\\)</span>. The comparative study of two paired T-junctions with reciprocal width-to-depth ratio (e.g., a deep-style T-junction, <span>\\(\\chi \\)</span> = 1/3 and a flat-style T-junction, <span>\\(\\chi \\)</span> = 3) explicitly illustrates that the geometrical confinement stabilizes the generation dynamics of droplets at T-junctions. The mechanism for the stabilization effect is discussed. It provides some new insights in terms of designing devices of droplets’ generation.</p></div>","PeriodicalId":706,"journal":{"name":"Microfluidics and Nanofluidics","volume":"27 10","pages":""},"PeriodicalIF":2.3000,"publicationDate":"2023-09-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Microfluidics and Nanofluidics","FirstCategoryId":"5","ListUrlMain":"https://link.springer.com/article/10.1007/s10404-023-02678-9","RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q2","JCRName":"INSTRUMENTS & INSTRUMENTATION","Score":null,"Total":0}
引用次数: 0
Abstract
Despite the fact that there are not a few relative studies, the effects of geometrical confinement on droplets’ generation at micro-T-junctions are not explicitly addressed. A three-dimensional volume of fluid (VOF) CFD model is developed here to study this classic microfluidics problem. The micro-T-junctions are designed with arms of a same hydraulic diameter but different width-to-depth ratios (\(\chi \) = 1/10–10), covering both deep-style (\(\chi <1)\) and flat-style T-junctions (\(\chi >1)\). It is found that the width-to-depth ratio (confinement style) shows complex effects on the dynamics of droplets’ generation. At \(\chi \le 1/10\), droplets are failed to be generated at the T-junctions. Compared to the normal T-junctions (\(\chi >1\)), the deep-style T-junctions (\(1/6<\chi <\) 1) show much higher generation frequency of droplets at \({\mathrm{Ca}}_{\mathrm{c}}>0.06\) and the volume of generated droplets scales with \({{\mathrm{Ca}}_{\mathrm{c}}}^{-1}\) instead of typical \({{\mathrm{Ca}}_{\mathrm{c}}}^{-0.33}\). The comparative study of two paired T-junctions with reciprocal width-to-depth ratio (e.g., a deep-style T-junction, \(\chi \) = 1/3 and a flat-style T-junction, \(\chi \) = 3) explicitly illustrates that the geometrical confinement stabilizes the generation dynamics of droplets at T-junctions. The mechanism for the stabilization effect is discussed. It provides some new insights in terms of designing devices of droplets’ generation.
期刊介绍:
Microfluidics and Nanofluidics is an international peer-reviewed journal that aims to publish papers in all aspects of microfluidics, nanofluidics and lab-on-a-chip science and technology. The objectives of the journal are to (1) provide an overview of the current state of the research and development in microfluidics, nanofluidics and lab-on-a-chip devices, (2) improve the fundamental understanding of microfluidic and nanofluidic phenomena, and (3) discuss applications of microfluidics, nanofluidics and lab-on-a-chip devices. Topics covered in this journal include:
1.000 Fundamental principles of micro- and nanoscale phenomena like,
flow, mass transport and reactions
3.000 Theoretical models and numerical simulation with experimental and/or analytical proof
4.000 Novel measurement & characterization technologies
5.000 Devices (actuators and sensors)
6.000 New unit-operations for dedicated microfluidic platforms
7.000 Lab-on-a-Chip applications
8.000 Microfabrication technologies and materials
Please note, Microfluidics and Nanofluidics does not publish manuscripts studying pure microscale heat transfer since there are many journals that cover this field of research (Journal of Heat Transfer, Journal of Heat and Mass Transfer, Journal of Heat and Fluid Flow, etc.).