Title: Coupled atomistic-continuum methods for fluids

Abstract: This talk consists of two parts. In the first part,
I will present a multiscale method for the study of fluid systems which have unknown constitutive relations and/or unknown
boundary conditions. The multiscale method captures the macroscale
behavior of a fluid system using an atomistic model for the stress
and/or boundary conditions. The method contains three main components:
a macroscale model (the conservation laws for mass and momentum),
a microscale model (molecular dynamics), and a link between
the two models. The macroscale and microscale models are coupled
in a seamless way that does not require going back and forth between
the macro and micro states of the system. I will discuss the coupling
scheme, its application to polymer fluids, and the major difficulties
in implementations.

In the second part of the talk, I will discuss the moving contact line
(MCL) problem. The difficult in this problem comes from the fact that
hydrodynamics with the no-slip boundary condition predicts a
non-integrable viscous stress at the MCL. I will present
a systematic study of the physical processes and various forces in the
contact line region using molecular dynamics. A continuum model for the
boundary condition is formulated based the MD results.