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【書報討論】107/11/1 國立交通大學機械工程學系 陳慶耀教授(兼工學院副院長、科技部熱流暨航太學門召集人)



演講者:國立交通大學機械工程學系 陳慶耀教授(兼工學院副院長、科技部熱流暨航太學門召集人)

講題:Viscous Fingering in Radial Displacement of Immiscible Reactive Fluids: Effects of Produced Surfactants

摘要:Numerical simulations are performed on an immiscible reactive interface where a less viscous fluid is injected to displace a more viscous fluid. Surfactants are produced on the viscous unstable instable interface to complicate the fingering instability. A highly accurate phase-field method is applied in the present study. Effects of various dimensionless control parameters are evaluated systematically, such as the Damkohler number, the Atwood number and inject number, which represent the reaction rate, injection strength and viscous contrast, respectively. Because of the formation of fountain flow within the finger, the produced surfactants tend to accumulate on the sides of fingers, and result in more vigorous side-branching instability. In particular conditions of intermediate Damkohler number and inject number, the interfacial tension appears apparent variation along the interface because of significant accumulation of surfactants of the sides of fingers. Non-monotonic trend of the prominence of fingering instability, observed in the experiments, are also qualitatively reproduced by numerical simulations as shown in the figure.