Selected Paper Summaries for the Research Excellence Framework 2021

CPL library

This paper presents an overview of the CPL library, software designed for coupling of computational fluid dynamics to molecular dynamics. The multiscale approach presented in this work was designed with industry as part of a BP ICAM grant for £210k and two six month dCSE projects. This allowed a new collaboration with Civil Engineer including an eCSE grants which paid for my previous post doctoral position (eCSE08-3) as well as a key component in the successful EPSRC grant (EP/P010393/1) for £388k. The users/collaborations base has grown to include academics at Imperial, Japan, Glasgow and Melbourne.

The pressure tensor across a liquid-vapour interface

In this work, we applied my control volume framework to a moving interface, providing a technique valid in all systems which allows unrepresented insight into the nature of the fluid-liquid interface. The work resulted in me being an invited speaker at a Faraday format conference in Austria and the multiphase framework is the basis for an EPSRC grant (EP/S019545/1) between Imperial, Edinburgh and Brunel for £1.5 million, currently with very good reviews (6-6-5).

A langevin model for fluctuating contact angle behaviour parametrised using molecular dynamics

In this work, the moving contact line motion is simulated using molecular dynamics (MD) and the results parametrised using probability density functions used to design a Langevin model for coupling to a continuum solver. The reviews were favourable so the editor chose this article as the cover of Soft Matter. After seeing this work and meeting, Mirco Magnini came to Imperial to work and we wrote the Dame Julia Higgins engineering grant award together. The expertise demonstrated resulted in a paid BP challenge day on upstream oil recovery and an invitation to write a review article in Langmuir.

A molecular dynamics simulation of the turbulent couette minimal flow unit

This single author paper presents the first ever simulation of turbulence using an all molecular dynamics (MD) simulation. Previously, such simulation scales were assumed to be impossible but it was achieved through a combination of careful parameter studies, heavily optimisation of my custom MD software for large scale computing and a year of running on a supercomputer. This work lead to me being asked to chair the general turbulence session at the 2017 APS Division of fluid dynamics conference, a number of invited talks and a meeting and email exchange with the father of MD, Prof. Berni Alder, who believes that this is the future of molecular simulation.

A localized momentum constraint for non-equilibrium molecular dynamics simulations

This paper uses my mathematical framework, [Smith et al (2012) PRE 85 5 056705], with minimisation principles from classical physics to derive an exact framework for coupling which generalises and unifies much of the existing literature. This work provides a complete underpinning framework for coupling and is a major factor in the award of the Margaret Fishenden prize for best thesis in the last 5 years. As a result, I was invited to work in Australia, establishing collaborations with Billy Todd and Peter Daivis (Paper and Royal Society Grant [IES/R3/170233]) and Carlos Braga (Paper). The fundamental work here resulted in me being invited to give the main talk at the first ever UK multiscale Special Interest Group.

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