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 James Sprittles, University of Warwick

Warwick welcomes Vinay Gupta who has started a 2-year Commonwealth Rutherford Fellowship in the Mathematics Institute.  Vinay's background is in exploiting moment methods to describe gas mixtures and granular gases.

David Emerson

Prof. David R Emerson, Daresbury Laboratory

Arnau Miro from the Universitat Politècnica de Catalunya won a HPC Europa-2 grant for a 13-week visit to the Daresbury group. Arnau will be working on advanced meshing and code coupling strategies and starts his visit mid-January.

Dr. Duncan Lockerby

Prof. Duncan Lockerby, University of Warwick

Following an international competition, Jason Reese has been awarded a prestigious Chair in Emerging Technologies by the Royal Academy of Engineering (RAEng). 

These Chairs “identify global research visionaries and provide them with long-term support to lead on developing emerging technology areas with high potential to deliver economic and social benefit to the UK”.

For 10 years from March 2018, Prof Reese will be funded by the RAEng within the Micro & Nano Flows partnership to develop a new platform technology in multi-scale simulation-driven design for industrial innovation and scientific endeavour.

Further info: https://www.raeng.org.uk/news/news-releases/2018/april/academy-funds-global-research-visionaries-to-advan

Duncan Dockar, PhD Student, University of Edinburgh

Boiling is an important feature in many engineering processes, such as in the steam cycle in many power plants. It is also a highly multiscale phenomenon, with boiling bubbles nucleating on nanoscale features of solid substrates and growing to sizes of the order of mm. Researchers at Massachusetts Institute of Technology (MIT) have demonstrated the drastic effects that alterations at the nanoscale can have on boiling nucleation with the use of surfactants. By applying a voltage to certain parts of a substrate, the surfactants effectively render the substrate hydrophobic and can rapidly induce boiling at very specific regions of the substrate.

The rate at which boiling can be switched on or off is also particularly impressive, although as we all know the ultimate test for how fast scientists can control a process is by syncing it up with classical music… MIT calls this piece “Ode to Bubbles”, enjoy!

Cho, H. J. et al. Turning bubbles on and off during boiling using charged surfactants. Nat. Commun. 6:8599 doi: 10.1038/ncomms9599 (2015)

Livio Gibelli, Research Fellow, University of Warwick

On July 5/9, I took part to the 12th AIMS Conference on Dynamical Systems, Differential Equations and Applications in Taipei.
This conference aims at fostering and enhancing interactions among mathematicians and scientist in general. It has featured 135 special sessions with a broad range of topics. Keynote lectures were given by famous mathematicians (A. Buffa, V. Calvez, S. Peng, J. Ball, just to cite a few).

AIMS Conference schedule at a glance

I was in particular interested to two special sessions devoted to kinetic theory: "Models and Numerical Methods in Kinetic Theory" (where I was invited to give a talk) and "Kinetic and Related Equations: Collisions, Mean Field, Organized Motion".
Although kinetic equations have been traditionally applied to rarefied gas dynamics and plasma physics, these special sessions have confirmed an emerging trend in kinetic theory, namely the use of its theoretical framework to study topics in fields which are apparently far from fluid dynamics like the emergence of organized collective behaviour in vehicular traffic, crowds, swarms, social systems and biology. This wide range of new applications and the benefits that these studies can potentially bring to the society has significantly revived the interest in kinetic theory.
A detailed description of sessions along with the abstracts of presented talk can be found at the conference's website (http://aimsciences.org/conferences/2018/).

Overall, I was pleased to partecipate to the conference. The only negative aspect was that typhoon Maria stroke Taipei the day I had to flight back home. As a consequence, my flight was delayed and I was forced to spend almost two days segregated in hotel!

Dr Juan C. Padrino, Research Fellow, University of Warwick

I recently attended the 31st International Symposium on Rarefied Gas Dynamics held at the University of Strathclyde in Glasgow, Scotland.  The event was a great success in all its facets.  There was a remarkable turnout and both the oral presentations and poster display were of the highest scientific level.  During the week-long event, we were delighted with several invited talks by some of the world’s leading figures in the field of rarefied gas dynamics.  Several members of the Micro- and Nano-Flows Group for Engineering based at Edinburgh, Warwick, or Daresbury, participated in the symposium in a variety of roles.

 

In this blog entry, I want to focus on a talk I attended, entitled “Periodically patterned radiometric pumps – Novel configurations and further applications” by A. Lotfian, E. Roohi, and S. Stefanov. It was delivered by Dr. S. Stefanov of the Bulgarian Academy of Sciences.  The worked consisted on the numerical simulation of the flow and temperature fields of the gas in the channel formed between a patterned or ratchet surface on one side and a flat or, alternatively, ratchet surface on the other.  The radiometric pumping effect is generated by imposing a uniform temperature difference between both surfaces and by periodically changing the reflective property of the surface in the ratchet, namely, by alternating between a section reflecting specularly and another diffusely. Another configuration studied consisted of alternating a hot surface section with a cold one on the same side.  The effect of these perturbations is to create a net force and flow along the direction of the surfaces.  This net force can be used to generate motion if one of the surfaces is allowed to move, such as with a rotor.

 

In total, they investigated seven novel configurations.  A configuration very similar to the ones considered in this work can be seen here. For the analysis, they used the solver dsmcFoam+, an implementation of Direct Simulation Monte Carlo (DSMC) in the open source package OpenFoam+, parallelized using MPI.  They found that the maximum pumping velocity is observed in a zigzag channel with teeth machined on both sides.  On the other hand, the maximum radiometric force was attained in a channel with a flat wall on one side and double ratchets on the other wall.

Details about a numerical study like the one described in this entry can be found in this open-access article.