BEGIN:VCALENDAR VERSION:2.0 PRODID:-//CERN//INDICO//EN BEGIN:VEVENT SUMMARY:Keynote 3 - Vorticity banding in shear-thickening suspensions DTSTART;VALUE=DATE-TIME:20181210T150000Z DTEND;VALUE=DATE-TIME:20181210T154000Z DTSTAMP;VALUE=DATE-TIME:20260523T113123Z UID:indico-contribution-500@lindico453.srv.lu.se DESCRIPTION:Speakers: Romain Mari (CNRS\, University Grenoble-Alpes\, Fran ce)\nDiscontinuous shear thickening of dense suspensions is a phenomenon i n which\, at a specific shear rate\, the viscosity increases discontinuous ly often by orders of magnitude. Recent modeling of the phenomenon suggest s that the viscosity jump in rate-controlled rheometry corresponds to an u nderlying S-shaped flow curve in stress-controlled conditions. This nonmon otonic rheology was observed in simulations with modest particle numbers\, showing a range of shear stresses for which the shear rate is a decreasin g function of the shear stress. In general\, however\, one expects that fo r large enough systems a decreasing flow curve leads to a mechanical linea r instability of the uniform flow and the appearance of banding or rheo-ch aos in the nonlinear regime. The exact mode of instability is nonetheless quite difficult to predict in absence of a proper tensorial constitutive m odel. In this talk I will show particle-based numerical simulations of thi ckening suspensions exhibiting an instability along the vorticity directio n and subsequent "traveling" vorticity bands. Interestingly\, because the mechanical description of the vorticity direction can be decoupled from th e flow and gradient directions\, a one-dimensional (scalar) constitutive m odel is enough to capture most of the features observed in the simulations . This model also gives hints as to the origin of the unsteady rheological response observed in experiments performed in similar conditions.\n\nhttp s://lindico453.srv.lu.se/event/67/contributions/500/ LOCATION:Elite Hotel Ideon Tera URL:https://lindico453.srv.lu.se/event/67/contributions/500/ END:VEVENT END:VCALENDAR