Forced instability of core-annular flow in capillary constrictions

Forced instability of core-annular flow in capillary constrictions

Non-Axisymmetric Instability of Core-Annular Flow

Stability of core-annular flow of water and oil in a vertical circular pipe is studied with respect to nonaxisymmetric disturbances. Results show that when the oil core is thin, the flow is most unstable to the asymmetric sinuous mode of disturbance, and the core moves in the form of corkscrew waves as observed in experiments. The asymmetric mode of disturbance is the most dangerous mode for qu...

Corrugated interfaces in multiphase core-annular flow

Microfluidic devices can be used to produce highly controlled and monodisperse double or multiple emulsions. The presence of inner drops inside a jet of the middle phase introduces deformations in the jet, which leads to breakup into monodisperse double emulsions. However, the ability to generate double emulsions can be compromised when the interfacial tension between the middle and outer phase...

Viscoelastic potential flow analysis of capillary instability

Analysis of the linear theory of capillary instability of threads of Maxwell fluids of diameter D is carried out for the unapproximated normal mode solution and for a solution based on viscoelastic potential flow. The analysis here extends the analysis of viscous potential flow [Int. J. Multiphase Flow 28 (2002) 1459] to viscoelastic fluids of Maxwell type. The analysis is framed in dimensionle...

Viscous Potential Flow Analysis of Capillary Instability

Capillary instability of a viscous fluid cylinder of diameter D surrounded by another fluid is determined by a Reynolds number J = V D `= `, a viscosity ratio m = a= ` and a density ratio ` = a= `. Here V = = ` is the capillary collapse velocity based on the more viscous liquid which may be inside or outside the fluid cylinder. Results of linearized analysis based on potential flow of a viscous...