Type of Publication: | Journal article |
Publication status: | Published |
URI (citable link): | http://nbn-resolving.de/urn:nbn:de:bsz:352-0-321954 |
Author: | Nicolas, Alexandre; Fuchs, Matthias |
Year of publication: | 2016 |
Published in: | Journal of Non-Newtonian Fluid Mechanics ; 228 (2016). - pp. 64-78. - ISSN 0377-0257. - eISSN 1873-2631 |
DOI (citable link): | https://dx.doi.org/10.1016/j.jnnfm.2015.12.010 |
Summary: |
In the vicinity of their glass transition, dense colloidal suspensions acquire elastic properties over experimental timescales. We investigate the possibility of a visco-elastic flow instability in curved geometry for such materials. To this end, we first present a general strategy extending a first-principles approach based on projections onto slow variables (so far restricted to strictly homogeneous flow) in order to handle inhomogeneities. In particular, we separate the advection of the microstructure by the flow, at the origin of a fluctuation advection term, from the intrinsic dynamics. On account of the complexity of the involved equations, we then opt for a drastic simplification of the theory, in order to establish its potential to describe instabilities. These very strong approximations lead to a constitutive equation of the White–Metzner class, whose parameters are fitted with experimental measurements of the macroscopic rheology of a glass-forming colloidal dispersion. The model properly accounts for the shear-thinning properties of the dispersions, but, owing to the approximations, the description is not fully quantitative. Finally, we perform a linear stability analysis of the flow in the experimentally relevant cylindrical (Taylor–Couette) geometry and provide evidence that shear-thinning strongly stabilises the flow, which can explain why visco-elastic instabilities are not observed in dense colloidal suspensions.
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Subject (DDC): | 530 Physics |
Keywords: | Rheology; Dense colloidal suspensions; Mode-coupling theory; Viscoelastic instability |
Link to License: | In Copyright |
Bibliography of Konstanz: | Yes |
NICOLAS, Alexandre, Matthias FUCHS, 2016. Shear-thinning in dense colloidal suspensions and its effect on elastic instabilities : From the microscopic equations of motion to an approximation of the macroscopic rheology. In: Journal of Non-Newtonian Fluid Mechanics. 228, pp. 64-78. ISSN 0377-0257. eISSN 1873-2631. Available under: doi: 10.1016/j.jnnfm.2015.12.010
@article{Nicolas2016Shear-33187, title={Shear-thinning in dense colloidal suspensions and its effect on elastic instabilities : From the microscopic equations of motion to an approximation of the macroscopic rheology}, year={2016}, doi={10.1016/j.jnnfm.2015.12.010}, volume={228}, issn={0377-0257}, journal={Journal of Non-Newtonian Fluid Mechanics}, pages={64--78}, author={Nicolas, Alexandre and Fuchs, Matthias} }
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