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SUMMARY:Consititutive modelling of time-dependent flows in frictional susp
 ensions - Mike Cates\, DAMTP
DTSTART:20211008T150000Z
DTEND:20211008T160000Z
UID:TALK162685@talks.cam.ac.uk
CONTACT:Prof. Jerome Neufeld
DESCRIPTION:This talk will summarize recent work towards a constitutive mo
 delling framework for dense granular suspensions. The aim is to create a t
 ime-dependent\, tensorial theory that can implement the physics captured i
 n steady state by the Wyart-Cates model of 2014. This model of shear thick
 ening suspensions supposes that lubrication films break above a characteri
 stic normal force so that frictional contact forces come into play: the re
 sulting non-sliding constraints can be enough to rigidify a system that wo
 uld flow freely at lower stresses. Implementing this idea for time-depende
 nt flows requires the introduction of several new concepts including a con
 figuration-dependent ‘jamming coordinate’\, and the decomposition of t
 he velocity gradient tensor into compressive and extensional components wh
 ich then enter the evolution equation for particle contacts in distinct wa
 ys (a key idea due to Helen Wilson and Jurriaan Gillissen). The resulting 
 approach is qualitatively successful in addressing both the collapse of st
 ress during flow reversal in shear flow\, and the ability of transverse os
 cillatory flows to unjam the system. However there is much work required t
 o refine this approach towards quantitative accuracy\, incorporating more 
 of the physics of contact evolution under flow as determined by close inte
 rrogation of particle-based simulations.
LOCATION:MR2\, Centre for Mathematical Sciences\, Wilberforce Road\, Cambr
 idge
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