“To slip or not to slip”

Water flows in hydrophilic and hydrophobic microchannels

Surface properties such as wetting and roughness may have significant effects on liquid behavior at the micro- and nano- scale. Recent experimental studies suggest that slip effects may be present when using Newtonian fluids near highly hydrophobic surfaces. The wall slip boundary condition may also be very sensitive to the exact molecular structure of the surfaces such that surface roughness of molecular dimension scale may be the cause of inhibition of slip effect. We are examining these effects in detail and with high accuracy using high-resolution mass flow measurements and direct measurement of the velocity in the 100 nm near the surface.

Water in hydrophillic microchannel

Water in hydrophobic microchannel