Berlin 2012 – scientific programme
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DY: Fachverband Dynamik und Statistische Physik
DY 32: Soft Matter II
DY 32.3: Talk
Friday, March 30, 2012, 10:30–10:45, MA 144
Gravitational-like collapse in a petri dish: shock waves in the capillary compactification of a colloidal patch — •Johannes Bleibel1,2, Siegfried Dietrich1,2, Alvaro Dominguez3, and Martin Oettel4 — 1Max-Planck-Institut für Intelligente Systeme, Stuttgart, Germany — 2Institut für theoretische und angewandte Physik, Universität Stuttgart, Stuttgart, Germany — 3Física Teórica, Universidad de Sevilla, Sevilla, Spain — 4Institut für Physik, WA 331, Johannes Gutenberg Universität Mainz, Mainz, Germany
Interfacially trapped, micrometer-sized colloidal particles interact via long-ranged capillary attraction which is analogous to two-dimensional screened Newtonian gravity with the capillary length λ as the tunable screening length. Using Brownian dynamics simulations, density functional theory, and analytical perturbation theory, we study the dynamics of a finitely-sized patch of colloids. Whereas the limit λ → ∞ corresponds to the global collapse of a self-gravitating fluid, for intermediate λ we predict theoretically and observe in simulations a ringlike density peak at the outer rim of the disclike patch, moving as an inbound shock wave [1]. For smaller l the dynamics crosses over to spinodal decomposition showing a coarsening of regions of enhanced density which emerge from initial fluctuations [1,2]. The influence of hydrodynamic interactions on this capillary collapse will be discussed.
[1] J. Bleibel, A. Domínguez, S. Dietrich, and M. Oettel, Phys. Rev. Lett. 107, 128302 (2011).
[2] J. Bleibel, A. Domínguez, M. Oettel, and S. Dietrich, Eur. Phys. J. E 34, 125 (2011).