Coarse-Grained Models of Complex Fluids at Equilibrium and Under Shear

Abstract

Complex fluids exhibit structure on a wide range of length and time scales, and hierarchical approaches are necessary to investigate all facets of their often unusual properties. The study of idealized coarse-grained models at different levels of coarse-graining can provide insight into generic structures and basic dynamical processes at equilibrium and non-equilibrium. In the first part of this lecture, some popular coarse-grained models for membranes and membrane systems are reviewed. Special focus is given to bead-spring models with different solvent representations, and to random-interface models. Selected examples of simulations at the molecular and the mesoscopic level are presented, and it is shown how simulations of molecular coarse-grained models can bridge between different levels. The second part addresses simulation methods for complex fluids under shear. After a brief introduction into the phenomenology (in particular for liquid crystals), different non-equilibrium molecular dynamics (NEMD) methods are introduced and compared to one another. Application examples include the behavior of liquid crystal interfaces and lamellar surfactant phases under shear. Finally, mesoscopic simulation approaches for liquid crystals under shear are briefly discussed.