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microchannel, contact angle, wetting, Taylor slug, computational fluid dynamics, T-junction


Wetting effects form a dimension of fluid dynamics that becomes predominant, precisely controllable and possibly useful at the micro-scale. Microfluidic multiphase flow patterns, including size, shape and velocity of fluidic particles, and mass and heat transfer rates are affected by wetting properties of microchannel walls and surface tensions forces between fluid phases. The novelty of this field, coupled to difficulties in experimental design and measurements, means that literature results are scarce and scientific understanding is incomplete. Numerical methods developed recently have enabled a shortcut in obtaining results that can be perceived realistic, and that offer insight otherwise not possible. In this work the effect of the contact angle on gas-liquid two-phase flow slug formation in a microchannel T-junction was studied by numerical simulation. The contact angle, varied from 0 to 140 degrees, influenced the interaction of the gas and liquid phases with the channel wall, affecting the shape, size and velocity of the slugs. The visualisation of the cross-sectional area of gas slugs allowed for insight into the existence of liquid flow along rectangular microchannel corners, which was affected by the contact angle and determined the occurrence of velocity slip. The velocity profile within the gas slugs was also found to change as a function of contact angle, with hydrophilic channels inducing greater internal circulation, compared to greater channel wall contact in the case of hydrophobic channels. These effects play a role in heat and mass transfer from channels walls and highlight the value of numeral simulation in microfluidic design.


5 August 2016: At the time of publication, Sheridan College author Rafael M. Santos was associated with the Katholieke Universiteit Leuven in Belgium.

The Version of Record of this manuscript has been published and is available in Chemical Engineering Communications [Vol 199, Issue 12, (2012)] [copyright Taylor & Francis], available online at:


Faculty of Applied Science & Technology


School of Chemical and Environmental Sciences


Chemical Engineering Communications



Peer Reviewed/Refereed Publication


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Creative Commons Attribution-Noncommercial-No Derivative Works 4.0 License
This work is licensed under a Creative Commons Attribution-Noncommercial-No Derivative Works 4.0 License.

Original Publication Citation

Santos, R.M., Kawaji, M. (2012). Developments on Wetting Effects in Microfluidic Slug Flow. Chemical Engineering Communications, 199(12), 1626-1641.