Manipulating shearinduced nonequilibrium transitions in colloidal films by feedback control
Abstract
Using Brownian Dynamics (BD) simulations we investigate nonequilibrium transitions of sheared colloidal films under controlled shear stress $\sigma_{\mathrm{xz}}$. In our approach the shear rate $\dot\gamma$ is a dynamical variable, which relaxes on a timescale $\tau_c$ such that the instantaneous, configurationdependent stress $\sigma_{\mathrm{xz}}(t)$ approaches a preimposed value. Investigating the dynamics under this "feedbackcontrol" scheme we find unique behavior in regions where the flow curve $\sigma_{\mathrm{xz}}(\dot\gamma)$ of the uncontrolled system is monotonic. However, in nonmonotonic regions our method allows to {\em select} between dynamical states characterized by different inplane structure and viscosities. Indeed, the final state strongly depends on $\tau_c$ relative to an {\em intrinsic} relaxation time of the uncontrolled system. The critical values of $\tau_c$ are estimated on the basis of a simple model.
 Publication:

Soft Matter
 Pub Date:
 2014
 DOI:
 10.1039/C4SM01414F
 arXiv:
 arXiv:1403.6994
 Bibcode:
 2014SMat...11..406V
 Keywords:

 Condensed Matter  Soft Condensed Matter
 EPrint:
 9 pages, 9 figures