INTERNATIONAL JOURNAL OF MULTIPHASE FLOW
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2019
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IF 2.829
Xin Huang,Limin He,Xiaoming Luo,Haoran Yin,Donghai Yang
Deformation and coalescence behaviors of water droplets in viscous fluid under a direct current electric field are investigated with experiments and numerical simulations. An electro-hydrodynamic model is developed based on fluid dynamics equations and electrostatic equations. A coupled level set and volume of fluid method is proposed to capture the dynamic interface. The numerical results are validated to be in good accordance with classic results in the literature. The effects of electric capillary number Ca and viscosity ratio λ on droplet deformation and coalescence are systematically analyzed. Two different droplet response modes are obtained, namely overdamping response and underdamping response. The conversion of response modes is discussed with the ( Ca, λ ) phase diagram. Moreover, the distributions of electric field and flow field before and after the droplets contact are compared and analyzed. Numerical results show the time evolution of liquid bridge is dominated by the interfacial tension and viscosity of continuous phase. The electric stress is extremely weak at the liquid bridge and has a slight influence on evolution of liquid bridge. The correlation formula between dimensionless liquid bridge radius and conical angle during the growth of liquid bridge is regressed. These results are helpful for the optimization of electro-coalescence process.
研究领域:
流体力学
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电动力学
✓ 已验证
产品关联
DOI
高影响因子
CHEMICAL ENGINEERING SCIENCE
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2018
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IF 3.306
Xin Sun,Chunying Zhu,Taotao Fu,Youguang Ma,Huai Z. Li
Dynamics for droplet breakup with tunnels and formation of satellite droplets in a symmetric microfluidic T-junction are investigated using a high-speed digital camera. The breakup process of droplet could be divided into four sequential stages: squeezing, transition, pinch-off, and thread rupture stages. Effects of the viscosity ratio of both phases λ , the capillary number of the continuous phase Ca c , and the dimensionless droplet length l 0 / w c on the breakup process of droplet are analyzed. In the squeezing stage controlled by squeezing pressure, the variation of the minimum width of the droplet neck with time could be scaled as a power-law relationship with exponent related to λ and l 0 / w c . The transition stage is dominated by the velocity of the fluid, and the pinch-off stage is mainly driven by the capillary force. For these two stages, the evolution of the minimum width of the droplet neck with the remaining time could be described as other power-law relationship with exponent related to λ . In the thread rupture stage controlled by viscous stresses of both phases and the surface tension, the minimum width of droplet neck decreases linearly with time, and the coefficient of the linear function depends on λ . Additionally, for the formation of satellite droplets, the size of satellite droplet increases with the increase of superficial velocity of the fluid and droplet viscosity. Furthermore, a critical capillary number 0.03 is observed in low viscosity of the droplet, which divides the variation of the size of the main satellite droplet with the capillary number into constant area and growth zone.
研究领域:
流体力学
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生物工程
✓ 已验证
产品关联
DOI
高影响因子
COLLOIDS AND SURFACES A-PHYSICOCHEMICAL AND ENGINEERING ASPECTS
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2022
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IF 5.518
Miaomiao Lu,Siying Xiang,Yajiang Huang,Guangxian Li
Compatibilization efficiency of nanoparticles (NPs) toward polymer blends has been reported to depend on the viscosity ratio. However, this effect is seldom considered in the case of rough NPs. In this study, fluorescently labeled hydrophobic silica (SiO 2 ) NPs with different roughness were synthesized, and the morphological stabilization efficiencies of these NPs toward flowing polyisobutylene/polyethylene glycol blends were evaluated in-situ by confocal laser scanning microscopy . The surface roughness was found to affect the stacking behavior of NPs at the blend interface and NPs with larger roughness were more effective in stabilizing the morphology of flowing blends. Moreover, the morphological stabilization efficiencies of rough NPs were found to depend largely on the viscosity contrast of blend components, which determined the coverage of NPs at the interfacial area of blends and could be tailored by the strength of the shear flow. Therefore, the viscosity ratio should be an important parameter to be considered when evaluating the compatibilization efficiency of rough NPs.
研究领域:
材料科学
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化学工程
✓ 已验证
DOI
高影响因子
CHEMICAL ENGINEERING SCIENCE
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2025
·
IF 4.3
Zehui Shang,Yinan Liu,Chunying Zhu,Taotao Fu,Xiqun Gao,Youguang Ma
The breakup of water-in-water droplets in a Y-junction microchannel was experimentally investigated, focusing on the unobstructed breakup mode due to its broad applicability. This process was divided into four stages: entering, squeezing, pinch-off, and filament rupture, based on the evolution of the neck width and its thinning rate. In the entering stage, neck thinning accelerates with increasing dispersed-phase flow rate Q d , droplet length l 0 , and two-phase viscosity ratio λ , and slows down with increasing continuous phase flow rate Q c . In the squeezing stage, the minimum neck width follows a power-law relation with time. The thinning rate increases with higher Q d , l 0 , and λ , whereas increasing Q c inhibits thinning. In the pinch-off stage, neck width decreases linearly with time, and the thinning is enhanced by higher Q c , Q d , and l 0 , but remains nearly independent of λ . The filament rupture stage follows a power-law thinning trend, and exhibits similar parameter dependencies, though satellite droplets may form at high Q d and Q c , and show increased instability at low viscosity. These findings offer insights into neck dynamics and interfacial rupture in low interfacial tension systems.
研究领域:
流体力学
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微流控技术
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软物质物理
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界面科学
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生物医学工程
✓ 已验证
产品关联
DOI
高影响因子
CHEMICAL ENGINEERING JOURNAL
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2021
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IF 13.273
Haozhe Yi,Taotao Fu,Chunying Zhu,Youguang Ma
The local deformation and the head-on coalescence dynamics of droplets in a cross-focused microchannel are experimentally investigated. The dynamic process of droplets after collision is divided into squeezing stage and decompressing stage, and the flow patterns are divided into squeezing coalescence, decompressing coalescence and non-coalescence based on the moment when the liquid film ruptures. The local nipples caused by the lubrication force in the thin film arise in the decompressing stage and facilitate coalescence. The effects of the dispersed to continuous-phase viscosity ratio and the concentration of surfactant to the dynamic process, operating range of each flow pattern, and the extent of local deformation are investigated, and the predictive equation of the nipple angle is proposed. This research combines the local deformation with coalescence and provides a reference for further understanding the mechanism of droplet coalescence.
研究领域:
微流控
·
流体力学
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胶体科学
✓ 已验证
DOI
高影响因子
危险品化学品经营许可证（带存储）