8th Liquid Matter Conference September 6-10, 2011 Wien, Austria ...

P5.122Wed 711:10-14:00Gravitational-like collapse in a petri dish: shock waves inthe capillary compactification of a colloidal patchMartin Oettel, 1 Johannes Bleibel, 2 Alvaro Dominguez, 3 and Siegfried Dietrich 21 Mainz University, Institute of Physics, Staudinger Weg 7 55128, Mainz, Germany2 MPI for Intelligent Systems, Stuttgart, Germany3 University of Seville, Sevilla, SpainInterfacially trapped, micrometer-sized colloidal particles interact via long-ranged capillaryattraction which is analogous to two-dimensional screened Newtonian gravity with the capillarylength l as the screening length. Using Brownian dynamics simulations, density functionaltheory, and analytical perturbation theory, we study the collapse of a finitely-sized patch ofcolloids. Whereas the limit l becoming infinitely large corresponds to the global collapse of aself-gravitating fluid, for intermediate l we predict theoretically and observe in simulations aringlike density peak at the outer rim of the disclike patch, moving as an inbound shock wave. Forsmaller l the dynamics crosses over to spinodal decomposition showing a coarsening of regionsof enhanced density which emerge from initial fluctuations. Experimental realizations of thiscrossover scenario appear to be well possible for colloids trapped at water interfaces and having aradius of around 10 micrometer [1].[1] A. Dominguez, M. Oettel, and S. Dietrich, Phys. Rev. E 82, 011402 (2010).122