1. Moving drops on chemically patterned and superhydrophobic surfaces.

It is now possible to design surfaces where the wettability varies in a controlled way on micron length scales. We are investigating how drops move and spread on these surfaces. If surfaces are patterned with micron-size posts they become superhydrophobic -- strongly water repellent. There are many examples where nature has exploited superhydrophobic designs, for example, on the surfaces of leaves to aid the run off of rainwater. We are using analytic and numerical approaches to help to understand the phase transitions and dynamics of drops on superhydrophobic surfaces.

Microscopic and mesoscopic swimmers move at low Reynolds number. This is equivalent to larger animals swimming through a bath of treacle. We are investigating how these creatures swim, in groups and near surfaces. Questions at the moment include how to design artificial swimmers to aid in, say, drug delivery, how to write down a continuum theory which will help to describe the motion of a large number of swimmers, and swimmers powered by Marangoni forces. For more details, please see Chris Pooley's web page.

Liquid crystals are typically long, thin molecules. A subtle competition between energy and entropy causes them to order in many different ways. Interaction between this ordering and a flow field leads to strongly non-Newtonian flow behaviour. We are studying the rheological properties of liquid crystals, particularly in the cholesteric and blue phases, and of liquid crystal--istropic fluid emulsions.

When a mixture of grains of two different sizes is shaken horizontally particles of different size and densities separate to form stripes. We are trying to understand why.

Last Updated: 26th September 2006