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

An experiment was performed herein to examine the near-wall water flow characteristics and bulk flow behavior in microchannels with a height of 6 μm (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 (6 μm 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.