Multiscale simulations of interfacial slip for polymer melts under shear flow

The low shear rate interfacial slip behaviors of nonentangled bead–spring polymer melts are firstly simulated using a multiscale method without constitutive relations and wall slip hypotheses. Two orders of magnitude less computation compared with pure molecular dynamics simulations offers the present multiscale method unique capability to resolve the low shear rate slip problems for complex fluids, and to explore the impacts of bulk viscosity and interfacial friction coefficient on slip phenomenon detailedly. Variation of wall–fluid interaction (WFI) can lead to completely opposite trends of rate-dependent slip. For weak WFI, two distinct slip regimes including rate-independent regime and rapid increase regime can be found due to the competition between bulk viscosity and interfacial friction coefficient. For moderate WFI, the complete dominance of the bulk viscosity leads to a linear relation between the slip length and the bulk viscosity and two distinct regimes composed of rate-independent regime and rapid decrease regime.