Liquid migration during extrusion of shear thickening suspensions

Condensed Matter lunchtime seminar

Liquid migration during extrusion of shear thickening suspensions

  • Event time: 1:00pm until 2:00pm
  • Event date: 11th March 2019
  • Speaker: (School of Physics & Astronomy, University of Edinburgh)
  • Location: Room 2511,

Event details

In many industrial applications dense suspensions are forced from a reservoir through a constriction into a smaller pipe or channel. Dilution of suspensions is often encountered as they travel through a constriction. This phenomenon, commonly referred to as liquid migration, LM, can lead to catastrophic consequences. 

We investigate LM during the extrusion of well-characterised shear-thickening suspensions. We find a critical concentration exists. Below this concentration suspensions can be extruded homogeneously, above it LM occurs. We show this critical concentration depends on a characteristic shear rate in the die and can be predicted by coupling the suspension shear rheology to a simplified 'suspension-balance' model describing the relative solid-liquid flow in response to local stress gradients. In addition, we demonstrate how x-ray imaging can be utilised to visualise LM as a suspension travels through a constriction and the impact this has on the suspension upstream of the constriction.

About Condensed Matter lunchtime seminars

This is a weekly series of informal talks given primarily by members of the soft condensed matter and statistical mechanics groups, but is also open to members of other groups and external visitors. The aim of the series is to promote discussion and learning of various topics at a level suitable to the broad background of the group. Everyone is welcome to attend..

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