| Project/Area Number |
21K14097
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| Research Category |
Grant-in-Aid for Early-Career Scientists
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| Allocation Type | Multi-year Fund |
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| Review Section |
Basic Section 19020:Thermal engineering-related
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| Research Institution | Kyushu University |
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Principal Investigator |
Wang Zhenying 九州大学, 工学研究院, 助教 (20896633)
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| Project Period (FY) |
2022-02-01 – 2024-03-31
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| Project Status |
Completed (Fiscal Year 2023)
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| Budget Amount *help |
¥4,680,000 (Direct Cost: ¥3,600,000、Indirect Cost: ¥1,080,000)
Fiscal Year 2022: ¥2,210,000 (Direct Cost: ¥1,700,000、Indirect Cost: ¥510,000)
Fiscal Year 2021: ¥2,470,000 (Direct Cost: ¥1,900,000、Indirect Cost: ¥570,000)
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| Keywords | 三相界線 / 蒸発 / 液滴 / 熱マランゴニ効果 / ラプラスプレッシャー / ファンデルワールス力 / three phase contact line / flow pattern / droplet / capillary / Marangoni flow / interfacial mass flux / wetting dynamics / droplet evaporation / capillary force / Three phase contact line / Nanostructure / Atomic Force Microscope / Precursor film / Wetting and spreading |
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| Outline of Research at the Start |
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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| Outline of Final Research Achievements |
Extesive explorations have been carried out on the flow structure and spreading law of three phase contact line. With numerical modelling, trajectory analysis, infrared thermography, and mathematical decomposition, we show 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. A spreading law of evaporative droplets is derived by extending 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 from 10-1 to 103 W/m/K. We further derive a universal criterion for the transition of flow pattern near three phase contact line of evaporating droplets, and quantify the spatiotemporal variations of capillary velocity and Marangoni velocity by mathematically decomposing the tangential velocity of interfacial flow.
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| Academic Significance and Societal Importance of the Research Achievements |
制御可能な液体輸送は、電子機器の冷却、化学分析、生物医学診断において重要な役割を果たす。アプリケーションにおける実際のケースでは、ほとんどの液体は揮発性であるため、通常は蒸発が伴う。本研究は、実際のシナリオに直接対応する、熱伝導性基板上で蒸発する液滴の予測可能な拡散と流動状態の理論的基盤を提供する。状態図による支配的なメカニズムの分解は、質量流束の強さや液体と固体の熱特性に対応する流れの遷移など、既存の文献で物議を醸している問題のいくつかに対する普遍的な基準を提供する。研究の結論は、液体と固体の特性がよく調和したエレクトロニクス冷却および熱管理デバイスの新しい技術の開発に応用できる。
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