Tuesday 12 June 2012
to 14:30 at
Pinaki Chaudhuri (University of Mainz and University of Düsseldorf)
Soft amorphous materials are ubiquitous in nature and significant for a variety of industrial applications. Understanding the mechanisms that build up flow in such system remains an outstanding problem. In recent times, there has been considerable focus on such flows in a confined geometry - these studies have been useful in providing insight into the complex properties as well as microscopic origin of the flow behaviour.
Using numerical simulations, we study the onset of flow, under confinement, in model glassy systems. Typically, amorphous systems yield when the applied stress exceeds a threshold value (the yield stress) - we show that the time-scales for the onset of steady state flow rapidly increase as the applied stress is lowered towards the threshold. Moreover we observe that, these time-scales depend on the nature of the imposed stress field (homogeneous or inhomogeneous). We demonstrate how a theoretical framework which incorporates the role of co-operative effects in sustaining flow in these materials, can explain the significance of the stress field in determining the flow thresholds for confined glassy systems.