Abstract

Particles’ motion in complex fluids displays a variety of deviations from classical Brownian motion, ranging from anomalous diffusion to Fickian yet non-Gaussian diffusion. Several models have been pro- posed to frame these phenomena, usually based on the overdamped approximation, as a consequence of the short timescales for momentum relaxation. Nonetheless, an alternative hydromechanic approach can provide useful insights, by directly accounting for fluid-particle interactions. In this poster presentation, we provide the hydromechanic description of motion in complex fluids, by means of a position-dependent friction factor η(x). A two transition times mean square displacement scaling results as a consequence of the static heterogeneous landscape reproduced by η(x). Moreover, following from a two experiments gedanken system, a global effective fluctuation-dissipation relation is recovered from this model of het- erogeneity, while its failure is shown if starting from the corresponding description in terms of a rough energy landscape.