Micro & Nano Flows for Engineering

The micro & nano flows group is a research partnership between the Universities of Warwick and Edinburgh, and Daresbury Laboratory. We investigate gas and liquid flows at the micro and nano scale (where conventional analysis and classical fluid dynamics cannot be applied) using a range of simulation techniques: molecular dynamics,  extended hydrodynamics, stochastic modelling, and hybrid multiscaling. Our aim is to predict and understand these flows by developing methods that combine modelling accuracy with computational efficiency.

Targeted applications all depend on the behaviour of interfaces that divide phases, and include: radical cancer treatments that exploit nano-bubble cavitation; the cooling of high-power electronics through evaporative nano-menisci; nanowire membranes for separating oil and water, e.g. for oil spills; and smart nano-structured surfaces for drag reduction and anti-fouling, with applications to low-emissions aerospace, automotive and marine transport.

 

EPSRC Programme Grant in Nano-Engineered Flow Technologies

Our work is supported by a number of funding sources (see below), including a 5-year EPSRC Programme Grant (2016-2020). This Programme aims to underpin future UK innovation in nano-structured and smart interfaces by delivering a simulation-for-design capability for nano-engineered flow technologies, as well as a better scientific understanding of the critical interfacial fluid dynamics.

We will produce software that a) resolves interfaces down to the molecular scale, and b) spans the scales relevant to the engineering application. As accurate molecular/particle methods are computationally unfeasible at engineering scales, and efficient but conventional fluids models do not capture the important molecular physics, this is a formidable multiscale problem in both time and space. The software we develop will have embedded intelligence that decides dynamically on the correct simulation tools needed at each interface location, for every phase combination, and matches these tools to appropriate computational platforms for maximum efficiency.

This work is strongly supported by nine external partners (see below).

Current Funding

  • “Nano-Engineered Flow Technologies: Simulation for Design across Scale and Phase” EPSRC Programme Grant EP/N016602/1 01/16-12/20 (£3.4M)
  • “The First Open-Source Software for Non-Continuum Flows in Engineering” EPSRC grants: EP/K038427/1 K038621/1 K038664/1 07/13-06/17 (£0.9M)
  • “Multiscale Simulation of Interfacial Dynamics for Breakthrough Nano/Micro-Flow Engineering Applications” ARCHER Leadership Project 11/15-10/17 (£60k in supercomputer computational resource)
  • “Skating on Thin Nanofilms: How Liquid Drops Impact Solids” Leverhulme Research Project Grant 08/16-08/19 (£146k funding a 3-year PDRA)

Partnerships

  • Airbus Group Ltd
  • AkzoNobel
  • Bell Labs
  • European Space Agency
  • Jaguar Land Rover
  • Oxford Biomedical Engineering (BUBBL)
  • TotalSim Ltd
  • Waters Corporation

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Latest news and blogs

Dr. Duncan Lockerby

Prof. Duncan Lockerby, University of Warwick

We're sad to say goodbye to Kayleigh Hyslop, who has been our Programme Administrator for the past year or so. Kayleigh is off to teach scuba diving in the British Virgin Islands (wouldn't we all, if we could?). We wish her all the best and thank her for her hard work in setting up the Programme; and particularly for making our `research creativity' day such a success.

The good news is that Andrea Cooper joined us at the end of May, and is settling into her new role fast. Andrea will be working two days a week, based in Engineering at Warwick. She's looking forward to working with everyone, and I'm sure you'll hear more from her soon!

Dr Jianfei Xie, Research Associate, University of Edinburgh

The members of MNF (from the University of Edinburgh) attended the 30th Scottish Fluid Mechanics Meeting, which took place on Friday 19 May 2017 at the University of Strathclyde, Glasgow (hopefully we will see the meeting photograph later)Our group members Dr Rohit Pillai and Sree Hari gave the poster and oral presentations (Wetting dynamics of nanodroplets on vibrating surface, and Bridge growth anomalies during nanodroplet coalescence) separately. It was a great opportunity to communicate with other researchers from different background (Mathematics, Mechanical Engineering and Bioengineering) and see the wide applications of their research to engineering and science problems (stability of oil/water bi-layer free filmheterogeneous porous media flows, cellar blood flow and nanodroplets). The next meeting will be held at the University of Aberdeen next year.

Dr Benzi John, Senior Computational Scientist, Daresbury Laboratory

Benzi John (PI) and David Emerson (Co-I) have successfully won about 32, 000 KAU (~ £18,000) frunding from EPSRC to run large-scale simulations on ARCHER. The project titled "High fidelity non-equilibrium DSMC flow simulations at scale using SPARTA" will run for 12 months, starting from August 1st 2017. More information here.

Dr Benzi John, Senior Computational Scientist, Daresbury Laboratory

Benzi John (PI) and David Emerson (Co-I) have successfully won about 32, 000 KAU (~ £18,000) frunding from EPSRC to run large-scale simulations on ARCHER. The project titled "High fidelity non-equilibrium DSMC flow simulations at scale using SPARTA" will run for 12 months, starting from August 1st 2017. 

ARCHER is the UK's national supercomputing service based around a Cray XC30 supercomputer. EPSRC offers access to ARCHER through calls for proposals to the Resource Allocation Panel (RAP) through which users can request significant amounts of computing resource. The main aim of our project is to investigate the potential for carrying out large-scale rarefied gaseous flow problems using SPARTA. SPARTA is an exascale-capable, open-source code very recently developed at Sandia National Laboratories, designed to work efficiently on massively parallel computers. Over the course of this project, we intend to carry out selected large scale DSMC simulations related to studying a) supersonic gas flow dynamics in the low-pressure regions of a mass spectrometer, b) droplet evaporation and c) aerodynamics of flow past bluff bodies like cylinder. We hope that HPC computing resources available on ARCHER, together with the codes' scaling capabilities, will enable us to carry out the necessary testing, benchmarking, and parallel simulations at a high-fidelity scale.

Jesse Pritchard , PhD Student, University of Warwick

Here is an article on the capillary breakup of armored liquid filaments, which are liquid columns wherein superhydrophobic particles reside on the liquid-air interface rather than in the bulk of the filament. The authors (Zou, Lin and Ji) conducted experiments using a high-speed camera to analyse the effects of the interfacial powder coverage on the filament breakup dynamics for a variety of powder sizes and how this related to a control experiment using 'pure liquid', for which there are established power-laws governing the minumum filament radius at points in time before pinch-off.

It was found that the thinning process for the filament can be split into three stages: (i) the armored liquid stage, (ii) the transition stage, and (iii) the liquid stage. The bulk of the work is on the dynamics of the armored liquid stage, in which the filament thins uniformly with an increased effective surface tension owing to the presence of the powder, and so maintains a larger minimum filament radius than its powder-less counterpart. The authors have found their own scaling law that governs the minimum filament radius during this stage and have a established a model that well approximates experiments with well-reasoned assumptions on the geometry of the system. When the minimum filament radius approaches the order of the average particle radius, the transition stage begins as the particles cause local deformation of the interface, increasing curvature and accelerating the thinning process. This continues until a time in which thinning can be modelled using power laws for 'pure liquids' in the final stages of thinning before capillary breakup, known as the liquid stage.

Dr Matthew K. Borg

Dr Matthew K. Borg, Lecturer in Mechanical Engineering, University of Edinburgh

Our recent research article has recently been accepted for publication in Physical Review Fluids. Our main results show that shear flow of water over thin gas nanofilms entrapped on a surface produces larger-than-expected local slip, with the Knudsen number of the gas playing a significant role. Figure 1 shows a snap shot of the molecular dynamics simulation which we setup to measure the hydrodynamic slip length ‘b’ of water flowing over nitrogen gas, with slip defined at the reference y = 0. Figure 2 shows our main results: we plot values for the original theoretical gas cushion model (GCM) that does not include any rarefaction effects, our molecular dynamics results in symbols, and the proposed theoretical model from kinetic theory – which we have called the rarefied gas cushion model (r-GCM). Insight from these results could possibly help design future self-cleaning surfaces or drag-reducing/anti fouling marine coatings.