Spatial scale invariance represents a remarkable feature of natural phenomena. A ubiquitous example is represented by miscible liquid phases undergoing diffusion. Theory and simulations predict that in the absence of gravity diffusion is characterized by long-ranged algebraic correlations. Experimental evidence of scale invariance generated by diffusion has been limited, because on Earth the development of long-range correlations is suppressed by gravity. Here we report experimental results obtained in microgravity during the flight of the FOTON M3 satellite. We find that during a diffusion process a dilute polymer solution exhibits scale-invariant concentration fluctuations with sizes ranging up to millimetres, and relaxation times as large as 1,000 s. The scale invariance is limited only by the finite size of the sample, in agreement with recent theoretical predictions. The presence of such fluctuations could possibly impact the growth of materials in microgravity.

Fractal fronts of diffusion in microgravity / A. Vailati, R. Cerbino, S. Mazzoni, C. J. Takacs, D. S. Cannell, M. Giglio. - In: NATURE COMMUNICATIONS. - ISSN 2041-1723. - 2:1(2011 Apr 19), pp. 290.290.1-290.290.5. [10.1038/ncomms1290]

Fractal fronts of diffusion in microgravity

A. Vailati
Primo
;
R. Cerbino
Secondo
;
M. Giglio
Ultimo
2011

Abstract

Spatial scale invariance represents a remarkable feature of natural phenomena. A ubiquitous example is represented by miscible liquid phases undergoing diffusion. Theory and simulations predict that in the absence of gravity diffusion is characterized by long-ranged algebraic correlations. Experimental evidence of scale invariance generated by diffusion has been limited, because on Earth the development of long-range correlations is suppressed by gravity. Here we report experimental results obtained in microgravity during the flight of the FOTON M3 satellite. We find that during a diffusion process a dilute polymer solution exhibits scale-invariant concentration fluctuations with sizes ranging up to millimetres, and relaxation times as large as 1,000 s. The scale invariance is limited only by the finite size of the sample, in agreement with recent theoretical predictions. The presence of such fluctuations could possibly impact the growth of materials in microgravity.
diffusion ; fluctuations ; light scattering ; shadowgraph ; microgravity
Settore FIS/01 - Fisica Sperimentale
Settore FIS/03 - Fisica della Materia
19-apr-2011
Article (author)
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/2434/157010
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