**Large slip effect at a nonwetting fluid-solid interface**

JL Barrat and L Bocquet, PHYSICAL REVIEW LETTERS, 82, 4671-4674 (1999).

DOI: 10.1103/PhysRevLett.82.4671

It is well known that, at a macroscopic level, the boundary condition
for a viscous fluid at a solid wall is one of "no slip." The liquid
velocity field vanishes at a fixed solid boundary. We consider the
special case of a liquid that partially wets the solid (i.e., a drop of
liquid, in equilibrium with its vapor on the solid substrate, has a
finite contact angle). Using extensive molecular dynamics simulations,
we show that when the contact angle is large enough, the boundary
condition can drastically differ (at a microscopic level) from a no-slip
condition. Slipping lengths exceeding 30 molecular diameters are
obtained for a contact angle of 140 degrees, characteristic of mercury
on glass. This finding may have important implications for the transport
properties in nanoporous media under such "nonwetting" conditions.
**S0031-9007(99)09329-1**.

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