Concentration fluctuations in a homogeneous mixture are in general small and confined to the molecular lengthscale. It has been recently predicted that stressed fluids should exhibit anomalously large fluctuations. We will show here that anomalously large fluctuations also occur when macroscopic concentration gradients relax to the uniform state via diffusion. The measurements have been taken by low angle static light scattering and shadowgraphs. We find that at larger wavevectors the amplitude of the fluctuations diverges as q-4. It is also found that gravity stabilizes at a constant value the fluctuations below a critical wavevector. We will present data on a mixture close to a consolution critical point. Recent results will also be presented on ordinary liquid mixtures, a polymer and a protein solution. These new results have been obtained by means of a quantitative shadowgraph technique. They confirm that giant fluctuations are always associated with mass flow due to diffusion across a macroscopic gradient

Brogioli, D., Vailati, A., Giglio, M. (2000). Giant fluctuations in diffusion processes. JOURNAL OF PHYSICS. CONDENSED MATTER, 12(8A), A39-A46 [10.1088/0953-8984/12/8A/305].

Giant fluctuations in diffusion processes

BROGIOLI, DORIANO COSTANTINO;
2000

Abstract

Concentration fluctuations in a homogeneous mixture are in general small and confined to the molecular lengthscale. It has been recently predicted that stressed fluids should exhibit anomalously large fluctuations. We will show here that anomalously large fluctuations also occur when macroscopic concentration gradients relax to the uniform state via diffusion. The measurements have been taken by low angle static light scattering and shadowgraphs. We find that at larger wavevectors the amplitude of the fluctuations diverges as q-4. It is also found that gravity stabilizes at a constant value the fluctuations below a critical wavevector. We will present data on a mixture close to a consolution critical point. Recent results will also be presented on ordinary liquid mixtures, a polymer and a protein solution. These new results have been obtained by means of a quantitative shadowgraph technique. They confirm that giant fluctuations are always associated with mass flow due to diffusion across a macroscopic gradient
Articolo in rivista - Articolo scientifico
non equilibrium fluctuations; diffusion process
English
A39
A46
8
Brogioli, D., Vailati, A., Giglio, M. (2000). Giant fluctuations in diffusion processes. JOURNAL OF PHYSICS. CONDENSED MATTER, 12(8A), A39-A46 [10.1088/0953-8984/12/8A/305].
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/10281/36529
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