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Roughness Effects on Continuous and Discrete Flows in Superhydrophobic Microchannels

Published online by Cambridge University Press:  20 August 2015

Junfeng Zhang  and
Daniel Y. Kwok
Junfeng Zhang*
Affiliation:
School of Engineering, Laurentian University, Sudbury, Ontario, P3E 2C6, Canada
Daniel Y. Kwok*
Affiliation:
School of Engineering, Laurentian University, Sudbury, Ontario, P3E 2C6, Canada
*
Corresponding author.Email:jzhang@laurentian.ca
Email:daniel.kwok@ucalgary.ca
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Abstract

The dynamic behaviors of continuous and discrete flows in superhydrophobic microchannels are investigated with a lattice Boltzmann model. Typical characters of the superhydrophobic phenomenon are well observed from our simulations, including air trapped in the surface microstructures, high contact angles, low contact angle hysteresis, and reduced friction to fluid motions. Increasing the roughness of a hydrophobic surface can produce a large flow rate through the channel due to the trapped air, implying less friction or large apparent slip. The apparent slip length appears to be independent to the channel width and could be considered as a surface property. For a moving droplet, its behavior is affected by the surface roughness from two aspects: the contact angle difference between its two ends and the surface-liquid interfacial friction. As a consequence, the resulting droplet velocity changes with the surface roughness as firstly decreasing and then increasing. Simulation results are also compared with experimental observations and better agreement has been obtained than that from other numerical method. The information from this study could be valuable for microfluidic systems.

Keywords

68.08.Bc05.70.Np83.50.RpLattice Boltzmann methodinterfacial slipsuperhydrophobicitysolid-fluid interactionroughness effectmicrochannels
Type
Research Article
Information
Communications in Computational Physics , Volume 9 , Issue 5 , May 2011 , pp. 1094 - 1105
Copyright
Copyright © Global Science Press Limited 2011

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