| Thu January 26th 2017 16:00 – 17:00 ZH286 | Seminar | Dynamics of confined non-cohesive granular systems Nicolás Mujica |
Details:One of the most noticeable collective motion of non-cohesive granular matter is clustering under certain conditions. In particular, when a quasi-two-dimensional monolayer of mono-disperse non-cohesive particles is vertically vibrated, a solid-liquid-like transition occurs when the driving amplitude exceeds a critical value. Here, the physical mechanism underlying particle clustering relies on the strong interactions mediated by grain collisions, rather than on grain-grain cohesive forces.In this talk I will review experimental studies on the dynamics of dry and confined granular matter. Depending on the vertical height and filling density the solid-liquid transition can be of either first or second order type. For both cases density fluctuations do not show strong variations at the transition, but local order varies strongly, either abruptly or continuously respectively, with a critical-like behavior in the second case. Based on careful experimental measurements we were able to obtain five independent exponents, which are consistent with model C of dynamical critical phenomena. In addition, at the solid-liquid coexistence, in average, the solid cluster resembles a drop, with a striking circular shape. We experimentally investigate the coarse-grained solid-liquid interface fluctuations, which turn out to be well described by the capillary wave theory. This allows us to measure the solid-liquid interface effective surface tension and mobility once the granular ``thermal" kinetic energy is determined. | ||
