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| 題名: | Controlling droplet bouncing and coalescence with surfactant |
| 作者: | 黃冠嶺;Pan, K.-L.;Tseng, Y.-H.;Chen, J.-C.;Huang, K.-L.;Wang, C.-H.;Lai, M.-C. |
| 貢獻者: | 工學院土木工程學系 |
| 關鍵詞: | Applied mathematics;Atmospheric conditions;Coalescence;Convection;Droplets;Dye dispersion;Dynamics;Emulsions;Gas-liquid systems;Gases;Interfaces;Marangoni convection;Mathematical models;Moisture content;Preservation;Surface tension;Surfactants;Water content |
| 日期: | 2016-07-25 |
| 上傳時間: | 2026-04-21 14:05:12 (UTC+8) |
| 出版者: | Cambridge University Press;Cambridge, UK: Cambridge University Press |
| 摘要: | 摘要： The collision between aqueous drops in air typically leads to coalescence after impact. Rebounding of the droplets with similar sizes at atmospheric conditions is not generated, unless with significantly large pressure or high impact parameters exhibiting near-grazing collision. Here we demonstrate experimentally the creation of a non-coalescent regime through addition of a small amount of water-soluble surfactant. We perform a direct simulation to account for the continuum and short-range flow dynamics of the approaching interfaces, as affected by the soluble surfactant. Based on the immersed-boundary formulation, a conservative scheme is developed for solving the coupled surface-bulk convection–diffusion concentration equations, which presents excellent mass preservation in the solvent as well as conservation of total surfactant mass. We show that the Marangoni effect, caused by non-uniform distributions of surfactant on the droplet surface and surface tension, induces stresses that oppose the draining of gas in the interstitial gap, and hence prohibits merging of the interfaces. In such gas–liquid systems, the repulsion caused by the addition of surfactant, as frequently observed in liquid–liquid systems such as emulsions in the form of an electric double-layer force, was found to be too weak to dominate in the attainable range of interfacial separation distances. These results thus identify the key mechanisms governing the impact dynamics of surfactant-coated droplets in air and imply the potential of using a small amount of surfactant to manipulate impact outcomes, for example, to prevent coalescence between droplets or interfaces in gases.
其他題名： J. Fluid Mech
出版者： Cambridge, UK: Cambridge University Press
出版日期： 2016-07-25
出處： Journal of fluid mechanics, 2016-07, Vol.799, p.603-636
資源來源： Alma/SFX Local Collection
版權： 2016 Cambridge University Press
識別號： ISSN: 0022-1120
識別號： EISSN: 1469-7645
識別號： DOI: 10.1017/jfm.2016.381 |
| 顯示於類別: | [土木工程學系 ] 期刊論文
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