Tools for Multiscale Simulation of Liquids Using Open Molecular Dynamics

摘要

This work presents a review of recent tools for multiscale simulations of liquids, ranging from simple Newtonian fluids to polymer melts. Particular attention is given to the problem of imposing the desired macro state into open microscopic systems, allowing for mass, momentum and energy exchanges with the environmental state, usually provided by a continuum fluid dynamics (CFD) solver. This review intends to highlight that most of the different methods developed so far in the literature can be joined together in a general tool, which I call opf;n MD. The development of OPEN MD should be seen as an ongoing research program. A link between the micro and macro methods is the imposition of the external conditions prescribed by the macro-solver at or across the boundaries of a microscopic domain. The common methodology is the use of external particle forces within the so called particle buffer. Under this frame, open MD requires minor modifications to perform state-coupling (i.e. imposing velocity and/or temperature) or flux exchange, or even any clever combination of both. This tool can be used either in molecular or mesoscopic-based research or in CFD based problems, which focus on mean flow effects arising from the underlying molecular nature. In this latter case an important goal is to allow for a general description of Non-Newtonian liquids, involving not only transfer of momentum in incompressible situations, but also mass and energy transfers between the micro and macro models.