Sedimentation in confined geometry
The most familiar form of driven motion in colloidal dispersions is surely sedimentation. Yet it remains remarkably poorly understood, not least due to the non-linear many-body nature of the problem. We were able to show that, depending on the initial conditions, sedimentation in confined systems can in fact be reduced to a readily soluble problem Royall et al, Phys Rev Lett ,98, 188304 (2007) . However, in the case of a non-uniform initial condition, a Rayleigh-Taylor-Like instability leads to chaotic behaviour and network formation. Nonetheless, inclusion of hydrodynamic coupling in computer simulations allows this non-equilibrium emergent behaviour to be quantitatively reproduced.
Schmidt M, Royall CP, Dzubiella J and van Blaaderen, A. 'Non-equilibrium sedimentation of colloids: Confocal microscopy and Brownian dynamics simulations’, J. Phys:Cond. Matter, 20 494222 (2008). PDF download .
Royall CP, Dzubiella, J, Schmidt, M and van Blaaderen, A,
'Nonequilibrium Sedimentation of Colloids on the Particle
Scale', Physical Review Letters, 98 188304