BEGIN:VCALENDAR
VERSION:2.0
PRODID:-//Talks.cam//talks.cam.ac.uk//
X-WR-CALNAME:Talks.cam
BEGIN:VEVENT
SUMMARY:Nonmonotonic flow curves and shear banding in granular flows - Dr 
 Christopher Ness\, University of Edinburgh
DTSTART:20250321T160000Z
DTEND:20250321T170000Z
UID:TALK227200@talks.cam.ac.uk
CONTACT:Professor Grae Worster
DESCRIPTION:Dense granular packings\, both dry and suspended in liquid\, a
 re among the most abundant materials on earth. They are relevant to manifo
 ld geophysical phenomena\, e.g.\, landslides and debris flows\, and to ind
 ustrial processes such as paste extrusion. Understanding their deformation
  and flow properties is thus of major practical importance. It is also of 
 fundamental interest in  statistical physics\, fluid mechanics and rheolog
 y.  Here we use particle simulations to map comprehensively the shear rheo
 logy of dry and wet granular matter comprising particles of finite stiffne
 ss\, in both fixed pressure and fixed volume protocols. At fixed pressure 
 we find nonmonotonic constitutive curves that are shear thinning\, whereas
  at fixed volume we find nonmonotonic constitutive curves that are shear t
 hickening. We show that the presence of one nonmonotonicity does not imply
  the other. Instead\, there exists a signature in the volume fraction meas
 ured under fixed pressure that\, when present\, ensures nonmonotonic const
 itutive curves at fixed volume. In the context of dry granular flow we sho
 w that gradient and vorticity bands arise under fixed pressure and volume 
 respectively\, as implied by the constitutive curves. For wet systems our 
 results are consistent with a recent experimental observation of shear thi
 nning at fixed pressure. Reconciling these rich banding dynamics with a de
 tailed mechanistic description accounting also for non-locality and bounda
 ry effects remains an open challenge.
LOCATION:MR2
END:VEVENT
END:VCALENDAR