Continuum–DEM modelling of fluid–solid transition in weakly compacted systems of polydisperse particles of varying shapes

Retief Lubbe

Host Institutions

University of Twente [ 24 months ]
Procter & Gamble Technical Centres Ltd [ 12 months ]


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I am Retief Lubbe from South Africa.  I received my honours degree in Physics at the University of Pretoria. During my studies I have developed high performance spatial partitioning algorithms for-GPU-Discrete Element Method (DEM). I later moved to Beijing, China and graduated from Tsinghua University with a masters degree in Geotechnical Engineering where I worked on applying GPU DEM at a representative volume element (RVE) level for high performance multi-scale problems and calibration of geomaterials. My current project moves past the solid regime of granular material into the transition from flowing and stopping. The objective is to find a viable continuum solution for this transition for various industrial processes.

Project Description

One of the main mechanical challenges in particle systems is the complex yielding transition from static to motion and back to jammed states. This creates considerable handling problems in industry for transport of particles, e.g., ensuring uniform flowability and composition until packages reach the consumer. Polydispersity and varying particle shapes add complexity to these handling problems.

Specific objectives are:
  1. Understand the effect of particle formulation on the contact network in the packed/static stage, with a focus on the role of history;
  2. Reproduce the complex transitions from static to motion and back using DEM simulations, and develop a continuum framework to capture this;
  3. Extend the micromechanically based continuum model to polydisperse, multi-component formulations of varying particle shapes;
  4. Understand segregation of multi-component systems within a closed packing subjected to many vibrations (like during transport to the client).
Expected Results:
  1. DEM data which reproduce the interplay between the yield transition from static to motion and back to jammed states;
  2. Continuum models which correctly capture these transitions;
  3. Extension of the model to bi-component (flow aids) and multi-component polydisperse particle systems.