Non-equilibrium molecular dynamics and continuum modelling of transient freezing of atomistic solids
File(s)
Accepted version
Author(s)
Font, Francesc
Micou, William
Bresme, Fernando
Type
Journal Article
Abstract
In this work we investigate the transient solidification of a Lennard-Jones liquid using non-equilibrium molecular dynamics simulations and continuum heat transfer theory. The simulations are performed in slab-shaped boxes, where a cold thermostat placed at the centre of the box drives the solidification of the liquid. Two well-defined solid fronts propagate outwards from the centre towards the ends of the box until solidification is completed. A continuum phase change model that accounts for the difference between the solid and the liquid densities is formulated to describe the evolution of the temperature and the position of the solidification front. Simulation results for a small and a large nanoscale system, of sizes 30.27 nm and 60.54 nm, are compared with the predictions of the theoretical model. Following a transient period of ~ 20-40 ps and a displacement of the solidification front of 1-2.5 nm we find that the simulations and the continuum theory show good agreement. We use this fact to combine the simulation and theoretical approaches to design a simple procedure to calculate the latent heat associated to the liquid-solid phase transition. We also perform simulations of the homogeneous freezing process, i.e. in the absence of a temperature gradient and at constant temperature, by quenching the liquid at supercooled temperatures. We demonstrate that, for comparable temperature conditions, the solidification rate of homogenous freezing is much faster than the one obtained under a thermal gradient. Our study and conclusions should be of general interest to a wide range of atomistic solids.
Date Issued
2021-01-01
Date Acceptance
2020-10-12
Citation
International Journal of Heat and Mass Transfer, 2021, 164, pp.1-11
ISSN
0017-9310
Publisher
Elsevier
Start Page
1
End Page
11
Journal / Book Title
International Journal of Heat and Mass Transfer
Volume
164
Copyright Statement
© 2020 Elsevier Ltd. All rights reserved. This manuscript is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International Licence http://creativecommons.org/licenses/by-nc-nd/4.0/
Sponsor
Engineering & Physical Science Research Council (EPSRC)
The Leverhulme Trust
Identifier
http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcApp=PARTNER_APP&SrcAuth=LinksAMR&KeyUT=WOS:000594277500086&DestLinkType=FullRecord&DestApp=ALL_WOS&UsrCustomerID=1ba7043ffcc86c417c072aa74d649202
Grant Number
EP/J003859/1
RPG-2018-384
Subjects
Science & Technology
Physical Sciences
Technology
Thermodynamics
Engineering, Mechanical
Mechanics
Engineering
Solidification
Phase change
Phase transitions
Nanoscale
Non-equilibrium molecular dynamics
Heat transfer theory
Stefan problem
Supercooling
INTERFACES
Publication Status
Published
Article Number
ARTN 120601
Date Publish Online
2020-10-23