Influence of Capillary Number on the droplet Shape, Film Thickness, and Pressure Drop in a Liquid-Liquid Taylor Flow inside a Microcapillary

• Published in: International journal of mathematical, engineering and management sciences Vol. 4; no. 6; pp. 1407 - 1419
• Main Authors: Vivekanand, S. V. B., Chandrasekhar, S., Raju, V. R. K.
• Format: Journal Article
• Language: English
• Published: Dehradun International Journal of Mathematical, Engineering and Management Sciences 01.12.2019; Ram Arti Publishers
• Subjects: Film thickness; Fluid mechanics; Heat conductivity; Mechanical engineering; Numerical analysis; Pressure drop; Taylor flow; Velocity; Volume of fluid method
• ISSN: 2455-7749; 2455-7749
• DOI: 10.33889/IJMEMS.2019.4.6-111

Numerical analysis of a two-dimensional, axisymmetric, incompressible, laminar liquid-liquid Taylor flow inside a vertical circular microchannel is carried out in the present study. The focus is laid on fluid flow characteristics in the slug flow regime. Although many researchers have performed numerical and experimental studies of two-phase flows in narrow channels, their efforts seem to have been fairly successful in explaining the underlying mechanisms of fluid flow phenomena, especially for slug flow regime. Here, an attempt has been made to explore the hydrodynamics of such flows. In the present study, dodecane and Pd5 have been used as the carrier phases and water is used as the discontinuous phase. The internal diameter of the circular microchannel is 1.5 mm with its wall being insulated. The flow and volume fraction equations are solved by the finite volume approach (FVM). The volume of fluid (VOF) method has been adopted for capturing the interface. The effect of Capillary number on film thickness and interfacial pressure drop is explained. The film thickness is found to increase with Capillary number and is also found to be in a close match with the models available in the literature. The pressure drop per unit length obtained from the CFD study is compared with a standard model available in the literature. The pressure drop across the unit cell is found to be following the phenomenological model. It is observed that the pressure drop at the interface has the highest contribution to the total pressure drop in contrast to the other pressure drops in the channel, with ~50-55% in dodecane-water and ~55-62% in Pd5-water systems. Besides, the distribution of the velocity, axial, and wall pressure fields inside the microcapillary are also discussed.