Center for Soft Matter Research, New York University, 4 Washington Place, New York, New York 10003, USA.
Phys Rev Lett. 2009 Dec 11;103(24):248301. doi: 10.1103/PhysRevLett.103.248301. Epub 2009 Dec 7.
Recent studies reveal that suspensions of neutrally buoyant non-brownian particles driven by slow periodic shear can undergo a dynamical phase transition between a fluctuating irreversible steady state and an absorbing reversible state. Using a computer model, we show that such systems exhibit self-organized criticality when a finite particle sedimentation velocity v(s) is introduced. Under periodic shear, these systems evolve, without external intervention, towards the shear-dependent critical concentration phi(c) as v(s) is reduced. This state is characterized by power-law distributions in the lifetime and size of fluctuating clusters. Experiments exhibit similar behavior and, as v(s) is reduced, yield steady-state values of phi that tend towards the phi(c) corresponding to the applied shear.
最近的研究表明，在缓慢的周期性剪切驱动下处于中性浮力的非棕色无规粒子悬浮液可以在波动的不可逆稳态和吸收的可逆态之间经历动力学相变。使用计算机模型，我们表明，当引入有限的颗粒沉降速度 v(s) 时，此类系统表现出自组织临界性。在周期性剪切下，这些系统在没有外部干预的情况下，随着 v(s) 的降低，向与剪切相关的临界浓度 phi(c) 演化。这种状态的特征是在波动簇的寿命和大小上呈现幂律分布。实验表现出类似的行为，并且随着 v(s) 的降低，产生趋于与所施加的剪切相对应的 phi(c) 的稳态值 phi。
