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Title

A new algorithm for extended nonequilibrium molecular dynamics simulations of mixed flow

Author(s)

Hunt, Thomas A.;  Bernardi, Stefano;  Todd, B. D.

Abstract

In this work, we develop a new algorithm for nonequilibrium molecular dynamics of fluids under planar mixed flow, a linear combination of planar elongational flow and planar Couette flow. To date, the only way of simulating mixed flow using nonequilibrium molecular dynamics techniques was to impose onto the simulation box irreversible transformations. This would bring the simulation to an end as soon as the minimum lattice space requirements were violated. In practical terms, this meant repeating the short simulations to improve statistics and extending the box dimensions to increase the total simulation time. Our method, similar to what has already been done for pure elongational flow, allows a cuboid box to deform in time following the streamlines of the mixed flow and, after a period of time determined by the elongational field, to be mapped back and recover its initial shape. No discontinuity in physical properties is present during the mapping and the simulation can, in this way, be extended indefinitely. We also show that the most general form of mixed flow, in which the angle between the expanding (or contracting) direction and the velocity gradient axis varies, can be cast in a so-called canonical form, in which the angle assumes values that are multiples of π (when a mixed flow exists), by an appropriate choice of the field parameters.

Publication type

Journal article

Research centre

Swinburne University of Technology. Faculty of Information and Communication Technologies. Centre for Molecular Simulation

Source

Journal of Chemical Physics, Vol. 133, no. 15 (Oct 2010), article no. 154116

Publication year

2010

FOR Code(s)

0202 Atomic, Molecular, Nuclear, Particle and Plasma Physics;  0306 Physical Chemistry (Incl. Structural)

Keyword(s)

Algorithm;  Mixed flow;  Nonequilibrium molecular dynamics

Publisher

American Institute of Physics

ISSN

0021-9606

Publisher URL

http://dx.doi.org/10.1063/1.3489683

Copyright

Copyright © 2010 American Institute of Physics. The published version of the paper is reproduced here with the kind permission of the publisher. This article may be downloaded for personal use only. Any other use requires prior permission of the author and the American Institute of Physics.

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