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Memory of colloidal suspension visualized as desiccation crack pattern

A densely packed colloidal suspension, called paste, remembers the direction of its motion, such as vibration and flow, due to its plasticity. The memory of such motion can be visualized as a morphology of desiccation crack patterns. When a water-poor paste is vibrated, the paste remembers the direction of the vibration even after the vibration stops, and desiccation cracks run in the direction perpendicular to the direction of the initial vibration [1]. On the other hand, when a water-rich paste is vibrated, the paste flows, and once the paste flows, it comes to remember its flow direction, and the desiccation cracks run in the direction parallel to the direction of the initial flow [2]. Since any flow pattern can be imprinted into a paste as a memory, memory effects of paste can be applied to produce various types of desiccation crack patterns, such as cellular, radial, lamellar, spiral, ring, and so on.
[1] A. Nakahara and Y. Matsuo, J. Phys. Soc. Jpn. 74 (2005) 1362.
[2] A. Nakahara and Y. Matsuo, Phys. Rev. E 74 (2006) 045102(R).

Author(s):

Akio Nakahara    
Nihon University
Japan

Yousuke Matsuo    
Nihon University
Japan