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Updated: Oct 29, 2025

The Diffusion of Passive Tracers in Laminar Shear Flow
Published on: May 1, 2018
Rheology based estimates of self- and collective diffusivities in viscous liquids
C Gainaru1, S Ahlmann1, L S Röwekamp1
1Fakultät Physik, Technische Universität Dortmund, D-44221 Dortmund, Germany.
Abstract:
The self-diffusion coefficient of viscous liquids is estimated on the basis of a simple analysis of their rheological shear spectra. To this end, the Almond-West approach, previously employed to access single-particle diffusivities in ionic conductors, is generalized for application to molecular dynamics in supercooled liquids. Rheology based estimates, presented for indomethacin, ortho-terphenyl, and trinaphthylbenzene, reveal relatively small, yet systematic differences when compared with diffusivity data directly measured for these highly viscous liquids. These deviations are discussed in terms of mechanical Haven ratios, introduced to quantify the magnitude of collective translational effects that have an impact on the viscous flow.
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