David Fairhurst

I am interested in complex fluids, the behaviour of liquids on surfaces, and more recently how animals interact with fluids.

I have supervised ten PhD students, on topics including how hair conditioner dissolves in water, the evaporation of droplets containing polymers, improving MRI images using bubbles, using hollow particles as food additives, and the control of fluid drag over surfaces.

My current research interests include:

Evaporation of liquid droplets – Although a seemingly trivial problem there are many competing physical process taking place when a droplet of liquid is left to dry on a solid surface: evaporation and phase change, heat flow, convection currents, molecular diffusion, phase change, capillary flow, Marangoni flow to name a few. Understanding the evaporation process has implications for heat flow applications. Furthermore, if the droplet contains non-volatile components, these will eventually be deposited on the surface in various patterns, such as the commonplace coffee stain in which the dark coffee grains are predominantly deposited around the edge, the centre of the droplet being much paler in colour. Understanding and controlling the final deposit is important for many industries from printing to crop spraying. My group was the first to discover that poly(ethylene oxide) deposits preferentially in the centre of the droplets, forming a pillar which can be taller than the initial droplet.
Complex fluids – Most everyday liquids contain a range of various components, which can interact in complex ways. Many foods and drinks contain micron-sized colloidal particles; detergents and cleaning products contain surfactant molecules which have one water-loving end and the other oil-loving end; long chain polymer molecules are added to many products to give particular material and flow properties. Our team's research in this broad field ranges from the phase behaviour of hard sphere colloidal suspensions, in particular the effect of polydispersity; the non-equilibrium behaviour and rheology of surfactant solutions; foam stability using novel molecules.
Biological Fluid Flow – All life interacts with fluids. We have studied two rather unusual creatures. One was bioluminescence in microscopic dinoflagellates - these are organisms that live in the sea and on certain calm evenings fill the water with a beautiful blue glow, in response to wave motion. We are interested to find out how exactly the organisms can sense the moving water, and to quantify the brightness and duration of their response. Secondly we are investigating the breeding behaviour of Bitterling fish, who carefully place their eggs into freshwater mussels using flexible ovipositor tubes.