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Quantifying active diffusion in an agitated fluid

Titelangaben

Gires, Pierre-Yves ; Thampi, Mithun ; Weiss, Matthias:
Quantifying active diffusion in an agitated fluid.
In: Physical Chemistry Chemical Physics. Bd. 22 (2020) Heft 38 . - S. 21678-21684.
ISSN 1463-9084
DOI: https://doi.org/10.1039/D0CP03629C

Abstract

Mixing of reactants in microdroplets predominantly relies on diffusional motion due to small Reynolds numbers and the resulting absence of turbulent flows. Enhancing diffusion in microdroplets by an auxiliary noise source is therefore a topical problem. Here we report on how the diffusional motion of tracer beads is enhanced upon agitating the surrounding aqueous fluid with miniaturized magnetic stir bars that are compatible with microdroplets and microfluidic devices. Using single-particle tracking, we demonstrate via a broad palette of measures that local stirring of the fluid at different frequencies leads to an enhanced but apparently normal and homogenous diffusion process, i.e. diffusional steps follow the anticipated Gaussian distribution and no ballistic motion is observed whereas diffusion coefficients are significantly increased. The signature of stirring is, however, visible in the power-spectral density and in the velocity autocorrelation function of trajectories. Our data therefore demonstrate that diffusive mixing can be locally enhanced with miniaturized stir bars while only moderately affecting the ambient noise properties. The latter may also facilitate the controlled addition of nonequilibrium noise to complex fluids in future applications.

Weitere Angaben

Publikationsform: Artikel in einer Zeitschrift
Begutachteter Beitrag: Ja
Institutionen der Universität: Fakultäten
Fakultäten > Fakultät für Mathematik, Physik und Informatik
Fakultäten > Fakultät für Mathematik, Physik und Informatik > Physikalisches Institut
Fakultäten > Fakultät für Mathematik, Physik und Informatik > Physikalisches Institut > Lehrstuhl Experimentalphysik I - Physik lebender Materie
Fakultäten > Fakultät für Mathematik, Physik und Informatik > Physikalisches Institut > Lehrstuhl Experimentalphysik I - Physik lebender Materie > Lehrstuhl Experimentalphysik I - Physik lebender Materie - Univ.-Prof. Dr. Matthias Weiss
Profilfelder > Advanced Fields > Nichtlineare Dynamik
Profilfelder
Profilfelder > Advanced Fields
Titel an der UBT entstanden: Ja
Themengebiete aus DDC: 500 Naturwissenschaften und Mathematik > 530 Physik
500 Naturwissenschaften und Mathematik > 570 Biowissenschaften; Biologie
Eingestellt am: 23 Feb 2021 12:52
Letzte Änderung: 26 Aug 2022 06:21
URI: https://eref.uni-bayreuth.de/id/eprint/63350