My work focuses on multi-scale fluids engineering systems: nano- and microfluidics, interfacial and other non-continuum flows, high-speed (rarefied) aerodynamics, and rapid granular/gas flows.
The engineering of flow systems across great length- and time-scales will play an important role in meeting societal challenges over the next 30 years; for example, nano-filtering seawater to make it drinkable for water-stressed populations, and embedding micro and nano devices in aeroplane and ship surfaces to improve fuel efficiency and reduce carbon dioxide emissions.
Multi-scale and multi-physics dynamics is characteristic of these areas of emerging technological importance, but affects the overall behaviour of the fluid flows in poorly-understood ways. This makes their simulation, design and control extremely difficult. The dynamics of the constituent fluid particles or molecules is key to understanding the overall flow behaviour.
I am investigating new ways of modelling and simulating these flows from both molecular and hydrodynamic viewpoints. In particular, developing theoretical insight into the underlying non-continuum physics, and numerical simulation tools ranging from compressible fluid codes running extended hydrodynamic models through to highly-parallel molecular dynamics and DSMC codes. I am also developing new kinds of hybrid software that combine particle and hydrodynamic solvers under one methodology.
All of these numerical tools are released open-source to work within the OpenFOAM code (www.openfoam.org).
Specific current research includes:
- designs for aligned-nanotube membranes for water purification and gas separation
- insight into water interactions with moving surfaces, applicable to drag reduction coatings
- exploiting scale separation in time and space to enable efficient hybrid computations
- the effect of molecular mean free path variation near a surface on gas micro flows
- near-surface rarefaction and molecular adsorption effects on gas micro flows
- high-order diffusive mechanisms in gas kinetic theory
- using particle and molecular methods to probe flows of engineering importance
Multi-scale and multi-physics dynamics is one of the grand challenges in science and engineering for the 21st century, which means the research is long-term, complex and diverse. While there is much work still to be done, our research results show the promise of our approaches in accurately capturing the behaviour of non-continuum and non-equilibrium flows in complex geometries in a range of applications.