Viscous co‐current downward Taylor flow in a square mini‐channel

Abstract

This article presents a computational study of the co-current downward Taylor flow of gas bubbles in a viscous liquid within a square channel of 1 mm hydraulic diameter. The three-dimensional numerical simulations are performed with an in-house computer code, which is based on the volume-of-fluid method with interface reconstruction. The computed (always axi-symmetric) bubble shapes are validated by experimental flow visualizations for varying capillary number. The evaluation of the numerical results for a series of simulations reveals the dependence of the bubble diameter and the interfacial area per unit volume on the capillary number. Correlations between bubble velocity and total superficial velocity are also provided. The present results are useful to estimate the values of the bubble diameter, the liquid film thickness and the interfacial area per unit volume from given values of the gas and liquid superficial velocities.

A general design procedure for gas–liquid Taylor flow T-junction microreactors

“…12(b) shows, the proportional coefficient is 0.836, which is close to that reported in the literature. 32…”

Numerical modeling of multiphase flows in microfluidics and micro process engineering: a review of methods and applications

“…The use of periodic boundary conditions in the axial direction allowed restriction of the computational domain to a single flow unit cell (which consists of one bubble and one liquid slug). The computed bubble shapes were compared with experimental flow visualizations and good agreement was obtained (Keskin et al 2010). In Ö ztaskin et al (2009) the interaction of equal sized Taylor bubbles separated by liquid slugs of different length was studied.…”

“…Liu and Wang (2008) extended this study to vertical square and equilateral triangular channels with 1 mm hydraulic diameter. Wörner and coworkers performed comprehensive numerical simulations of concurrent upward and downward Taylor flow in millimeter sized square vertical channels with an in-house PLIC-VOF code (Ghidersa et al 2004;Wörner et al 2005;Wörner et al 2007;Ö ztaskin et al 2009;Keskin et al 2010). The use of periodic boundary conditions in the axial direction allowed restriction of the computational domain to a single flow unit cell (which consists of one bubble and one liquid slug).…”

Liquid velocity distribution in slug flow in a microchannel

“…2. The bubble cross-sectional area, A b , for a fully developed Taylor bubble was estimated based on the assumption that the film thicknesses on the top and bottom surfaces of the microchannel were very thin (\0.01 lm for d/D * Ca 2/3 ) and that the interface between the bubble and the microchannel corners had a semicircular contour (Wong et al 1995a;Hazel and Heil 2002;Ajaev and Homsy 2006;De Lózar et al 2008;Keskin et al 2010). However, the two circular contours of the microchannel sidewall and the bubble interface did not have the same central location in the y-direction and therefore, the key step to estimate the bubble cross-sectional area was to determine the bubble interface location in the y-direction.…”