ICAMS / Interdisciplinary Centre for Advanced Materials Simulation


Flow heterogeneity in hard-sphere glasses: connecting MD studies with lattice Boltzmann simulations

Date: 18.07.2012
Place: Bridging the Scales in Glasses, Heinrich-Heine-Universität, Düsseldorf, Germany

Segun Ayodele
Dierk Raabe, Max-Planck-Institut für Eisenforschung GmbH, Düsseldorf, Germany
Fathollah Varnik

There is growing  evidence that the flow of driven amorphous solids is not homogeneous, even if the macroscopic stress is constant across the system [1,2]. Via event driven molecular dynamics simulations of a hard-sphere glass, we provide first direct evidence for a correlation between the fluctuations of the local volume-fraction and the fluctuations of the local shear rate [3]. Higher shear rates do preferentially occur at regions of lower density and vice versa. The temporal behavior of fluctuations is governed by a characteristic time scale, which, when measured in units of strain, is independent of shear rate in the investigated range. Interestingly, the correlation volume is also roughly constant for the same range of shear rates. A possible connection between these two observations is discussed.

[1] F. Varnik, L. Bocquet, J.-L. Barrat, L. Berthier, Phys. Rev. Lett. 90, 095702  (2003).
[2] R. Besseling, L. Isa, P. Ballesta, G. Petekidis, M.E. Cates, W.C.K. Poon, Phys. Rev. Lett. 105, 268301 (2010).
[3] S. Mandal, M. Gross, D. Raabe, F. Varnik, Phys. Rev. Lett. 108, 098301 (2012).

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