Evaporation of Nanofluid Sessile Droplets Under Marangoni and Buoyancy Effects: Internal Convection and Instability
Previous research has studied the evolution of patterns during the evaporation of sessile droplets of pure liquid, although there is a lack of reports focusing on the transition of flow regimes and flow stability of nanofluids. In this study, we investigate the evaporation of sessile droplets of Al&...
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MDPI AG
2025-02-01
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| author | Yuequn Tao Zhiqiang Zhu |
| author_facet | Yuequn Tao Zhiqiang Zhu |
| author_sort | Yuequn Tao |
| collection | DOAJ |
| description | Previous research has studied the evolution of patterns during the evaporation of sessile droplets of pure liquid, although there is a lack of reports focusing on the transition of flow regimes and flow stability of nanofluids. In this study, we investigate the evaporation of sessile droplets of Al<sub>2</sub>O<sub>3</sub>-ethanol nanofluid to elucidate the dynamic characteristics of the evaporation process from the perspective of internal convection. As the temperature increases, internal convection intensifies, significantly accelerating the evaporation rate. Three distinct convection flow patterns are observed under the combined influence of the Marangoni effect and buoyancy during evaporation: initially, two macroscopic convection cells form, followed by the periodic generation and propagation of hydrothermal waves (HTWs) near the contact line. Subsequently, Bénard–Marangoni (BM) convection cells gradually emerge and ultimately dominate the flow dynamics. The deposition patterns, which differ in part from the classic coffee-ring pattern, are closely related to the flow patterns of HTWs and BM convection cells during the pinning stage of droplet evaporation. Furthermore, the critical Marangoni (Ma) and Rayleigh (Ra) numbers for the onset of convection flow instability increase with rising substrate heating temperature. |
| format | Article |
| id | doaj-art-40ba37d5373140fe8af273bcbee7d458 |
| institution | DOAJ |
| issn | 2079-4991 |
| language | English |
| publishDate | 2025-02-01 |
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| series | Nanomaterials |
| spelling | doaj-art-40ba37d5373140fe8af273bcbee7d4582025-08-20T02:44:56ZengMDPI AGNanomaterials2079-49912025-02-0115430610.3390/nano15040306Evaporation of Nanofluid Sessile Droplets Under Marangoni and Buoyancy Effects: Internal Convection and InstabilityYuequn Tao0Zhiqiang Zhu1National Microgravity Laboratory, Institute of Mechanics, Chinese Academy of Sciences, Beijing 100190, ChinaNational Microgravity Laboratory, Institute of Mechanics, Chinese Academy of Sciences, Beijing 100190, ChinaPrevious research has studied the evolution of patterns during the evaporation of sessile droplets of pure liquid, although there is a lack of reports focusing on the transition of flow regimes and flow stability of nanofluids. In this study, we investigate the evaporation of sessile droplets of Al<sub>2</sub>O<sub>3</sub>-ethanol nanofluid to elucidate the dynamic characteristics of the evaporation process from the perspective of internal convection. As the temperature increases, internal convection intensifies, significantly accelerating the evaporation rate. Three distinct convection flow patterns are observed under the combined influence of the Marangoni effect and buoyancy during evaporation: initially, two macroscopic convection cells form, followed by the periodic generation and propagation of hydrothermal waves (HTWs) near the contact line. Subsequently, Bénard–Marangoni (BM) convection cells gradually emerge and ultimately dominate the flow dynamics. The deposition patterns, which differ in part from the classic coffee-ring pattern, are closely related to the flow patterns of HTWs and BM convection cells during the pinning stage of droplet evaporation. Furthermore, the critical Marangoni (Ma) and Rayleigh (Ra) numbers for the onset of convection flow instability increase with rising substrate heating temperature.https://www.mdpi.com/2079-4991/15/4/306droplet evaporationnanofluidthermal convectionconvection instability |
| spellingShingle | Yuequn Tao Zhiqiang Zhu Evaporation of Nanofluid Sessile Droplets Under Marangoni and Buoyancy Effects: Internal Convection and Instability Nanomaterials droplet evaporation nanofluid thermal convection convection instability |
| title | Evaporation of Nanofluid Sessile Droplets Under Marangoni and Buoyancy Effects: Internal Convection and Instability |
| title_full | Evaporation of Nanofluid Sessile Droplets Under Marangoni and Buoyancy Effects: Internal Convection and Instability |
| title_fullStr | Evaporation of Nanofluid Sessile Droplets Under Marangoni and Buoyancy Effects: Internal Convection and Instability |
| title_full_unstemmed | Evaporation of Nanofluid Sessile Droplets Under Marangoni and Buoyancy Effects: Internal Convection and Instability |
| title_short | Evaporation of Nanofluid Sessile Droplets Under Marangoni and Buoyancy Effects: Internal Convection and Instability |
| title_sort | evaporation of nanofluid sessile droplets under marangoni and buoyancy effects internal convection and instability |
| topic | droplet evaporation nanofluid thermal convection convection instability |
| url | https://www.mdpi.com/2079-4991/15/4/306 |
| work_keys_str_mv | AT yuequntao evaporationofnanofluidsessiledropletsundermarangoniandbuoyancyeffectsinternalconvectionandinstability AT zhiqiangzhu evaporationofnanofluidsessiledropletsundermarangoniandbuoyancyeffectsinternalconvectionandinstability |