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arXiv · 1112.1493

On the nonlocal viscosity kernel of mixtures

Ben Smith·J. S. Hansen·B. D. Todd
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Abstract

In this report we investigate the multiscale hydrodynamical response of a liquid as a function of mixture composition. This is done via a series of molecular dynamics simulations where the wave vector dependent viscosity kernel is computed for three mixtures each with 7-15 different compositions. We observe that the nonlocal viscosity kernel is dependent on composition for simple atomic mixtures for all the wave vectors studied here, however, for a model polymer melt mixture the kernel is independent of composition for large wave vectors. The deviation from ideal mixing is also studied. Here it is shown that a Lennard-Jones mixture follows the ideal mixing rule surprisingly well for a large range of wave vectors, whereas for both the Kob-Andersen mixture and the polymer melt large deviations are found. Furthermore, for the polymer melt the deviation is wave vector dependent such that there exists a critical length scale at which the ideal mixing goes from under-estimating to over-estimating the viscosity.

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Ben Smith, J. S. Hansen, B. D. Todd. 2011-12-07. On the nonlocal viscosity kernel of mixtures. https://doi.org/10.1103/physreve.85.022201

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