| 研究課題/領域番号 |
21K14097
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| 研究種目 |
若手研究
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| 配分区分 | 基金 |
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| 審査区分 |
小区分19020:熱工学関連
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| 研究機関 | 九州大学 |
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研究代表者 |
王 振英 九州大学, 工学研究院, 助教 (20896633)
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| 研究期間 (年度) |
2022-02-01 – 2024-03-31
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| 研究課題ステータス |
交付 (2022年度)
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| 配分額 *注記 |
4,680千円 (直接経費: 3,600千円、間接経費: 1,080千円)
2022年度: 2,210千円 (直接経費: 1,700千円、間接経費: 510千円)
2021年度: 2,470千円 (直接経費: 1,900千円、間接経費: 570千円)
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| キーワード | wetting dynamics / three phase contact line / droplet evaporation / capillary force / Marangoni flow / Three phase contact line / Nanostructure / Atomic Force Microscope / Precursor film / Wetting and spreading |
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| 研究開始時の研究の概要 |
The project aims to realize high-resolution observation of three phase contact line with relative motion taking place at the liquid-solid interface. The spatiotemporal evolution detected by AFM will be numerically fitted with Direct Numerical Simulation (DNS) based on the precursor film theory.
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| 研究実績の概要 |
Extensive investigations have been carried out on the wetting dynamics of evaporative droplets, as the fact that the spreading and flow transition in volatile droplets remains controversial due to the complexity added by interfacial phase change and non-equilibrium thermal transport. We show, using both mathematical modeling and experiments, that the wetting dynamics of volatile droplets can be scaled by the spatial temporal interplay between capillary, evaporation, and thermal Marangoni effects. We quantify these complex interactions using phase diagrams based on detailed theoretical and experimental analyses. We further illustrate the spreading law of droplets by generalizing Tanner’s law (valid for non-volatile liquids) to a full range of liquids with saturation vapor pressure spanning from 101 to 104 Pa and on substrates with thermal conductivity spanning from 10-1 to 103 W/m/K. Besides its importance in fluid-based industries, the conclusions also enable a unifying explanation to a series of individual works including the criterion of flow reversal and the state of dynamic wetting, making it possible to control liquid transport in diverse application scenarios. The findings to date have been summarized and will be submitted recently.
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| 現在までの達成度 (区分) |
現在までの達成度 (区分)
2: おおむね順調に進展している
理由
Due to the limitation of time resolution of Atomic Force Microscopy on contact line tracing, we have shifted the exploration to the wetting dynamics of evaporative droplets with detailed investigations of the flow structure near the three-phase contact line. The research combines numerical simulation and experimental visualization. With a newly developed model and comprehensive experimental verifications, we are able to reach a big picture of the spreading dynamics of evaporative liquids on solids. Besides its importance in fluid-based industries, the conclusions also enable a unifying explanation to a series of individual works including the criterion of flow reversal and the state of dynamic wetting, making it possible to control liquid transport in diverse application scenarios.
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| 今後の研究の推進方策 |
In the next fiscal year, the flow structure near the three-phase contact line (TPCL) will be traced and comprehensively investigated with a micro-PIV setup based on an inverted fluorescence microscope. Especially, we will investigate the transition of the flow field near TPCL with stepwise increasing strength of interfacial phase change. The visualization results will be compared with the numerical data, which can provide rich information and elucidate the flow interaction (capillary flow and Marangoni flow) near TPCL. We will further conduct experiments on substrates with varying surface wettability or with wettability gradients, aiming to relate the flow field near TPCL with the visualized droplet dynamics as well as the deposition patterns.
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