Non-equilibrium structure formation and anomalous diffusion with and without orientational degrees of freedom (*may move to Tues if walk does not take place)
Meeting Room 2, CMS
AbstractWe detail results of two microscopic models for active media integrated numerically. In the first, point particles lacking orientational degrees of freedom are driven individually through random force noise, and dissipate energy collectively through inelastic interactions. This leads to large length-scale density fluctuations (aka 'giant number fluctuations') and super-diffusion, and we provide a simple scaling argument that links the two, suggestion a degree of commonality between these two features. A simple mechanism relating this model to those with orientational degrees of freedom is postulated. The second model is of apolar filaments driven by two-headed motile springs mimicking motor proteins, in quasi-2D systems with and without lateral confinement. With confinement, a range of structure formation is observed akin to in vitro experiments and in vivo visualisation of dividing cells. Without confinement, layers, asters and bundled states are found that broadly a gree with the predictions of a simple model. Super-diffusion is also observed for less strongly-bound states, as is a suggestion of giant number fluctuations. It is hoped this bottoms-up approach may lead to analytical theories for active gels valid on length scales on the filaments, relevant to some biological situations.
Co-authors: G. Gompper (Juelich, Germany), W. J. Briels (Twente, The Netherlands), H. Tanaka (Tokyo University)