Critical transition in fiber suspension

A single buoyant fiber in a low Reynolds shear flow has a fully determined motion, so-called Jeffery orbit. However, the behavior of a concentrated fiber suspension remains unclear; even slight interactions between objects can disturb the system [1]. The non-reversible motion of the fiber suspension in oscillatory flow is monitored with a) quantitative image analysis and b) measurement of the in-phase torque response. A dynamical phase transition from a quasi-reversible state to a fluctuating one is observed as the strain amplitude is increased over a threshold at which the transient time exhibits a power law divergence. We discuss here the nature of this transition and its universality class. The main features of this transition are consistent with earlier results on sphere suspensions [2, 3], such systems might be one of the few realizations of conserved directed percolation [4].\\[4pt] [1] Okagawa A and al, Science, Volume 181, Issue 4095, p159 (1973)\\[0pt] [2] Pine DJ and al, Nature, vol 438, Issue 7070, p997 (2005)\\[0pt] [3] Corte L and al, Nature physics, vol 4, Issue 5, p420 (2008)\\[0pt][4] Menon GI and al, PrE, vol 79, 061108 (2009)