Abstract
Using Couette and Poiseuille flows, we extract the temperature dependence of the slip length, , from molecular dynamics simulations of a coarse-grained polymer model in contact with an attractive surface. is dictated by the ratio of bulk viscosity and surface mobility. At weakly attractive surfaces, lubrication layers form; is large and increases upon cooling. Close to the glass transition temperature , very large slip lengths are observed. At a more attractive surface, a sticky surface layer is built up, giving rise to small slip lengths. Upon cooling, decreases at high temperatures, passes through a minimum, and grows for . At strongly attractive surfaces, the Navier-slip condition fails to describe Couette and Poiseuille flows simultaneously. The simulations are corroborated by a schematic, two-layer model suggesting that the observations do not depend on details of the computational model.
- Received 5 April 2008
DOI:https://doi.org/10.1103/PhysRevLett.101.026101
©2008 American Physical Society