Velocity measurements in DI water flow microchannels with hydrophilic and hydrophobic surfaces

•Slip length, as well as slip velocity, have been found for all the cases studied.•The contacted angle makes the influence on the friction factor.•It is found that the wall effect is more significant. An experiment was performed herein to examine the near-wall water flow characteristics and bulk flo...

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Bibliographic Details
Published in:Applied thermal engineering 2017-12, Vol.127, p.901-905
Main Authors: Hsieh, Shou-Shing, Li, Shih-Yang, Hsieh, Yu-Cheng
Format: Article
Language:English
Subjects:
Flow characteristics
Flow velocity
Friction factor
Hydrophilic surfaces
Hydrophobic surfaces
Microchannel
Microchannels
Near-wall
nPIV
Slip
Slip velocity
Studies
Velocity distribution
Water flow
Wettability
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Summary:•Slip length, as well as slip velocity, have been found for all the cases studied.•The contacted angle makes the influence on the friction factor.•It is found that the wall effect is more significant. An experiment was performed herein to examine the near-wall water flow characteristics and bulk flow behavior in microchannels with a height of 6μm (velocity), through the optical measuring techniques of nPIV. Both the hydrophilic and hydrophobic surfaces of non-OTS, OTS, DTS and BTS were studied, and the corresponding velocity distribution, slip velocity and slip length (6μm channel) were measured. Moreover, the friction factor data were secured. The friction factor was correlated into a power law form in terms of the relevant parameters, including surface wettability, which is f=67.8Re-0.984θ∗-0.349 for both the hydrophilic and hydrophobic surfaces under study, and compared to those of previous studies with good agreement.
ISSN:1359-4311
1873-5606
DOI:10.1016/j.applthermaleng.2017.08.101