Random Organization in Periodically Driven Systems

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Original entry by Sagar Bhandari, APPHY 225 Fall 2010

Reference

Random Organization in Periodically Driven Systems, Laurent Corte, Paul M. Chaikin, J.P. Gollub, and David J. Pine, Nature Physics 4, 420 (2008).

Keywords

self-organization, periodically driven, particle suspensions

Summary

In this paper, the authors present a model for describing the self organization produced by irreversible collisions which generally produce chaotic dynamics. The authors mention that such a self organization can lead to a non-fluctuating quiescent state. The model was designed to model solid plastic particles suspended in a viscous liquid undergo reversible periodic trajectories when the suspension is sheared back and forth through a strain amplitude as shown in Fig 1. The idea is that the particles collide with each other and move an irreversible path.

Figure 1:

Sagar wiki8 image1.jpg

The results of the simulation is as shown below in Fig 2. This is the plot of time it takes to reach the quiescent point as a function of the strain amplitude.

Figure 2:

Sagar wiki8 image2.jpg

To confirm and test the agreement of the model with experiment, the results from an experiment was used. In this experiment, the system consists of small plastic particles suspended in a viscous liquid that is density and index matched to the particles. The suspensions are placed between concentric cylinders where the inner cylinder is rotated about its axis back and forth through a small angle to produce an oscillatory time-dependent strain. The period of oscillation is kept constant while changing the strain. The plot of experimental results for the characteristic time to reach the quiescent point as a function of strain amplitude is shown in Fig 3. It can be noticed that the behavior is very similar to as predicted by the model.

Figure 3:

Sagar wiki8 image3.jpg