Self-assembly of hydrodynamic flow
Particle ordering induced by dynamical interactions alone
Institute of Industrial Science
“Self-organization” describes the phenomenon of the spontaneous emergence of complex structures and systems. As one example of this phenomenon, just as a school of fish swimming in water takes on a particular shape, particles moving in a liquid flow sometimes spontaneously take on complex structures. As phenomena that appear in both the natural world and in living organisms, these phenomena have recently been the focus of much research interest. However, until now the mechanism behind the self-organization of moving particles in liquid flow remained unknown.
A research group led by Professor Hajime Tanaka of the Institute of Industrial Science, the University of Tokyo, discovered through numerical simulations that it is possible to realize a variety of states found in condensed matter, such as crystalline and glass states, through just the dynamic interaction of liquid vortices created by the rotation of particles. Although the spatial arrangement of the particles is fixed, these states are characterized by the violent flow of the surrounding fluid. A major characteristic of such structures is that the structure is stabilized through the self-organization of the liquid flow. This self-organization in a liquid flow is completely different to the normal concept of self-organization in that it is realized entirely from the flow alone and does not require any form of static interaction, something that had been considered necessary.
This result should open up new avenues of research into self-organization through the demonstration that it is possible to control the spatial arrangement of particles using liquid flow alone.
Purely hydrodynamic ordering of rotating disks at a finite Reynolds number", Nature Communications, 6 Article number 5994, doi: 10.1038/ncomms6994.
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