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Frequency-dependent complex viscosity obtained for a liquid two-dimensional dusty plasma experiment
Journal article   Open access   Peer reviewed

Frequency-dependent complex viscosity obtained for a liquid two-dimensional dusty plasma experiment

Jorge Berumen and J. Goree
Physical review. E, Vol.105(1), 015209
01/01/2022
DOI: 10.1103/PhysRevE.105.015209
PMID: 35193194
url
https://www.osti.gov/biblio/1863410View
Open Access

Abstract

Strongly coupled plasmas in a liquid phase can be characterized by a complex viscosity eta(w), which is a function of frequency. Data from a single experiment with dusty plasma were analyzed to compare eta(w) obtained by two fundamentally distinct methods. In a nonequilibrium method, a pair of counterpropagating laser beams, separated by a gap, applied a sinusoidal shear to a two-dimensional liquid, and eta(w) was determined using the constitutive relation. In an equilibrium method, there was no externally applied shear, so eta(w) could be calculated with a generalized Green-Kubo relation. The results for these two methods are compared for the real and imaginary parts of eta(w). For both parts, it is confirmed that the two methods yield results that agree qualitatively in their trends with frequency, with the real part diminishing with w and the imaginary part increasing with w, as expected for viscoelastic liquids. Quantitatively, the values of eta(w) obtained by the two methods differ slightly. For the experiment that we analyze, values for the real and imaginary parts of eta(w) are substantially greater than those reported in an earlier experiment, which we attribute to shear thinning effects in the earlier experiment. The experiment we analyze was designed to minimize shear thinning, unlike the earlier experiment.
Physical Sciences Physics Physics, Fluids & Plasmas Physics, Mathematical Science & Technology

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