Fluctuations and continuity in particle-continuum hybrid simulations of unsteady flows based on flux-exchange

¹ Centre for Computational Science, Chemistry Department, University College London 20 Gordon Street, London WC1H OAJ, UK
² Departamento de Ciencias y Técnicas Fisicoquímicas, Facultad de Ciencias, UNED Senda del Rey 9, 28040 Madrid, Spain
³ Physics Department, Oslo University - PB 1048 Blindern, 0316 Oslo, Norway

Corresponding authors: r.delgado-buscalioni@ucl.ac.uk e.g.flekkoy@fys.uio.no p.v.coveney@ucl.ac.uk

Received: 21 September 2004
Accepted: 14 January 2005

Abstract

This letter describes the treatment of unsteady liquid flow by a hybrid particle-continuum scheme. The scheme couples a particle region described by molecular dynamics with a coarse-grained domain solved by continuum fluid dynamics. The particle and continuum domains overlap in the coupling region, where two-way transfer of momentum flux is established. We demonstrate that this flux-coupling scheme is able to describe high-frequency oscillatory flows and to ensure the continuity of velocity across the particle-continuum interface. The effect of fluctuations within the particle system is also analysed and establishes the range in frequency and flow wave number for which hydrodynamic fluctuations need to be taken into account within the continuum description.