Droplet Pub Date : 2025-01-05 DOI: 10.1002/dro2.147

Youchen Ning, Yunhua Gan, Chuanshuai Dong, Ronghui Qi

{"title":"Numerical simulations and experimental verifications at micro-, meso-, and macroscales of droplet evaporation: A comprehensive review with special focus on saline droplets","authors":"Youchen Ning, Yunhua Gan, Chuanshuai Dong, Ronghui Qi","doi":"10.1002/dro2.147","DOIUrl":"https://doi.org/10.1002/dro2.147","url":null,"abstract":"Evaporation of saline droplets significantly impacts industrial processes such as water and gas treatment. Simulations, with advantages in describing temperature, concentration, and velocity distribution inside the droplet, receive increasing attentions. This paper summarized research on numerical simulations of droplet evaporation at micro-, meso-, and macroscales, emphasizing saline or multicomponent droplets. Accurate description of physics at phase interfaces and within proves to be critical for modeling. While recent studies have investigated on interface motion and temperature distribution, the coupling effect of internal concentration and flow distribution is still rarely considered. Among numerical methods, the lattice Boltzmann method is suitable for droplet scale due to its ability to handle non-continuum behavior. Bridging multiscale models remains a challenge, particularly in describing Marangoni and capillary flows. Experimental approaches to the effects of external physical fields (electric, magnetic, convection, and laser) and substrate properties on evaporation were also reviewed. Visualizing evaporation under various conditions can validate macroscopic models, while experiments with different substrates can validate molecular scale simulations, as substrate properties primarily affect evaporation by affecting capillary flow at the droplet bottom. This paper comprehensively reviewed numerical research on droplet evaporation, and analyzed the advantages, limitations, and development directions of various numerical methods.","PeriodicalId":100381,"journal":{"name":"Droplet","volume":"4 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2025-01-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/dro2.147","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143112361","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}

引用次数: 0

Sugar detection using drop evaporation 液滴蒸发法测糖

Droplet Pub Date : 2025-01-05 DOI: 10.1002/dro2.150

Yixiao Qu, Zhengyuan Ma, Min Zhang, Xing Huang, Lujia Xuan, Rui Ding, Wenya Liao, Zhiqiang Wu, Yihe Lin, Kami Hu, Zheng Liu, Ruoyang Chen, Hui He

{"title":"Sugar detection using drop evaporation","authors":"Yixiao Qu, Zhengyuan Ma, Min Zhang, Xing Huang, Lujia Xuan, Rui Ding, Wenya Liao, Zhiqiang Wu, Yihe Lin, Kami Hu, Zheng Liu, Ruoyang Chen, Hui He","doi":"10.1002/dro2.150","DOIUrl":"https://doi.org/10.1002/dro2.150","url":null,"abstract":"Evaporation deposition of a spilt sugary drop on the supporting surface can attract ants to surround it. People have a long history of using this phenomenon as an implication of sugar in the drop. Unfortunately, it is hard to detect sugar concentration and has to depend exclusively on ants. Here, we show a facile strategy for the eye-naked detection on sugar concentrations in common liquid mixtures, based on their evaporation depositions. Our experiments show that evaporation drops without any sugar form clear ring-like depositions, and the width of the ring area enlarges with the increase in sugar concentration. We demonstrate that the increase in sugar concentration can increase the liquid viscosity and decrease the capillary flow velocity, thus weakening the “coffee ring” effect. Our further experiments indicate that the temperature has insignificant effects on the correlation between sugar concentrations and ring-like depositions, but the substrate wettability impacts on the correlation by promoting the formation of ring-like depositions. Based on the mechanism study, we develop a strategy for detecting sugar concentrations via quantitatively correlating them with the width of the ring area, and demonstrate that it is valid for various liquid mixtures, for example, carbonate beverage, liquid medicine, and plant nutrient. Our findings not only present new insights into the understanding of the sugary drop evaporation, but also provide a facile strategy of detecting sugar concentration that promises great applications in food safety, pharmaceutical detection, and agricultural product measurements.","PeriodicalId":100381,"journal":{"name":"Droplet","volume":"4 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2025-01-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/dro2.150","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143112359","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}

引用次数: 0

Integrated copper-based Janus thermal system for efficient water harvesting around the clock 集成铜基Janus热系统，可全天候高效收集水

Droplet Pub Date : 2025-01-05 DOI: 10.1002/dro2.152

Congji Zhang, Guopeng Chen, Shangzhen Xie, Shuo Li, Ke Feng, Zhiguang Guo

{"title":"Integrated copper-based Janus thermal system for efficient water harvesting around the clock","authors":"Congji Zhang, Guopeng Chen, Shangzhen Xie, Shuo Li, Ke Feng, Zhiguang Guo","doi":"10.1002/dro2.152","DOIUrl":"https://doi.org/10.1002/dro2.152","url":null,"abstract":"Many regions across the globe are grappling with water scarcity issues, prompting the exploration of innovative water harvesting techniques. While the development of high-performance water harvesting materials has been widely documented, these technologies often rely on a singular source with limited efficiency. This study presents a dual-functional copper Janus system that facilitates continuous freshwater harvesting by integrating seawater desalination powered by solar energy during daylight hours and fog collection during night and morning time. The Janus system consists of a copper sheet and copper foam substrate, featuring superhydrophilic pores arranged on the superhydrophobic surface, as well as superhydrophilic flake-like structures made of soot-carbon particles, which are deposited on the framework of the copper foam. The fog collection rate of this system has been measured at 210.65 kg m−2 h−1, while the solar-driven evaporation rate of seawater under 1-sun conditions is reported at 1.44 kg m−2 h−1. The fog collection and evaporation efficiency have been enhanced by 28.72% and 183.27%, respectively. Furthermore, the system demonstrates strong and consistent performance even after repeated use, ensuring sustained water collection over prolonged periods. Therefore, this study presents a promising avenue for water collection technologies and offers valuable insights for the advancement of sustainable freshwater production methods.","PeriodicalId":100381,"journal":{"name":"Droplet","volume":"4 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2025-01-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/dro2.152","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143112356","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}

引用次数: 0

Front Cover, Volume 3, Number 4, October 2024 封面，第 3 卷第 4 号，2024 年 10 月

Droplet Pub Date : 2024-10-23 DOI: 10.1002/dro2.154

Chuanning Zhao, Youngjoon Suh, Yoonjin Won

引用次数: 0

Inside Back Cover, Volume 3, Number 4, October 2024 封底内页，第 3 卷第 4 号，2024 年 10 月

Droplet Pub Date : 2024-10-23 DOI: 10.1002/dro2.157

Zhi Tao, Weidong Fang, Haiwang Li, Shuai Yin, Tiantong Xu, Teckneng Wong, Yi Huang

引用次数: 0

Inside Front Cover, Volume 3, Number 4, October 2024 封面内页，第 3 卷第 4 号，2024 年 10 月

Droplet Pub Date : 2024-10-23 DOI: 10.1002/dro2.156

Ratima Suntornnond, Wei Long Ng, Viktor Shkolnikov, Wai Yee Yeong

引用次数: 0

Back Cover, Volume 3, Number 4, October 2024 封底，第 3 卷第 4 号，2024 年 10 月

Droplet Pub Date : 2024-10-23 DOI: 10.1002/dro2.155

Shile Feng, Yongping Hou, Yongmei Zheng

引用次数: 0

Aerodynamic breakup of emulsion droplets in airflow 气流中乳化液液滴的气动破碎

Droplet Pub Date : 2024-09-24 DOI: 10.1002/dro2.146

Zhikun Xu, Jinzhao Liu, Houpeng Zhang, Tianyou Wang, Zhizhao Che

{"title":"Aerodynamic breakup of emulsion droplets in airflow","authors":"Zhikun Xu, Jinzhao Liu, Houpeng Zhang, Tianyou Wang, Zhizhao Che","doi":"10.1002/dro2.146","DOIUrl":"https://doi.org/10.1002/dro2.146","url":null,"abstract":"Aerodynamic breakup refers to the process where large droplets are fragmented into small droplets by the aerodynamic force in airflow, which plays a vital role in fluid atomization and spray applications. Previous research has primarily concentrated on the aerodynamic breakup of single-component droplets, but investigations into the breakup of emulsion droplets are limited. This study experimentally investigated the aerodynamic breakup of water-in-oil emulsions in airflow, utilizing high-speed photography to observe the breakup process and digital in-line holography to measure fragment sizes. Comparative analyses between emulsion droplets and single-component droplets are conducted to examine the breakup morphology, breakup regime, deformation characteristics, and fragment size distributions. The emulsion droplets exhibit higher apparent viscosity and shorter stretching lengths of the bag film and peripheral rim due to the presence of a dispersed phase. The breakup regime transitions of emulsions are modeled by integrating the viscosity model of emulsions and the transition model of the pure fluid. The fragment sizes of emulsion droplets are larger due to the shorter lengths of the bag film and peripheral rim.","PeriodicalId":100381,"journal":{"name":"Droplet","volume":"3 4","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/dro2.146","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142555364","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}

引用次数: 0

Electro-coalescence of heterogeneous paired-droplets under AC electric field 交流电场下异质成对液滴的电凝聚

Droplet Pub Date : 2024-09-13 DOI: 10.1002/dro2.145

Zhi Tao, Weidong Fang, Haiwang Li, Shuai Yin, Tiantong Xu, Teckneng Wong, Yi Huang

{"title":"Electro-coalescence of heterogeneous paired-droplets under AC electric field","authors":"Zhi Tao, Weidong Fang, Haiwang Li, Shuai Yin, Tiantong Xu, Teckneng Wong, Yi Huang","doi":"10.1002/dro2.145","DOIUrl":"https://doi.org/10.1002/dro2.145","url":null,"abstract":"Controllable droplet coalescence exhibits unique advantages and intriguing prospect in chemical synthesis and biological engineering. Current researches focusing on the droplets of the same physics are, however, limited in terms of the interaction between different reactants. In this work, the electro-coalescence of heterogeneous paired-droplets is investigated in a microfluidic chip controlled by an AC electric field. The characteristics of merging dynamics are analyzed under different electric conditions and fluid properties, and an on-chip cross-linking reaction is conducted to enable the instantaneous production of hydrogel microspheres. We find that the coalescence of heterogeneous paired-droplets expands the range of start positions and prolongs the merging time compared to homogeneous paired-droplets. The evolution process of interfaces is accelerated with the increasing voltage, which contributes to the mixing of diverse components. Different electrical conductivities lead to distinct internal mechanisms within droplets. The voltage across the droplet is reduced with the increasing conductivity, while the enhanced attraction between free charges plays a complimentary role in interface instability. Lowering the surface tension reduced the required electric conditions for coalescence. Endowed with the non-Newtonian property, the droplet presents a non-linear relationship in the coalescence region, triggering coalescence with filaments at low voltages and showcasing superior performance at high frequencies. Based on above findings, we successfully produce alginate hydrogel microspheres with a wide range of concentrations in high monodispersity, achieving a clean fabrication of pure hydrogel without any additives and no need for subsequent cleaning. These results reveal the electro-hydrodynamics of heterogeneous paired-droplets, promoting the development of droplet coalescence in chemical and material science.","PeriodicalId":100381,"journal":{"name":"Droplet","volume":"3 4","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/dro2.145","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142555351","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}

引用次数: 0

DropletMask: Leveraging visual data for droplet impact analysis DropletMask：利用可视化数据进行液滴影响分析

Droplet Pub Date : 2024-09-03 DOI: 10.1002/dro2.137

Chuanning Zhao, Youngjoon Suh, Yoonjin Won

引用次数: 0

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