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Direct numerical simulations of dense granular suspensions in laminar flow under constant and varying shear rates
  • Sudharsan Srinivasan,
  • Harry Van den Akker,
  • Orest Shardt
Sudharsan Srinivasan
University of Limerick
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Harry Van den Akker
University of Limerick
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Orest Shardt
University of Limerick
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Abstract

Using an immersed boundary-lattice Boltzmann method, we investigated the response of dense granular suspensions to time-varying shear rates and flow reversals. The apparent viscosity and the evolution of particle clusters were analysed. The solids fractions and particle Reynolds numbers varied over the ranges 5% ≤ φv ≤ 47% and 0.11 ≤ Rep ≤ 0.32. The simulations included sub-grid scale corrections for unresolved lubrication forces. The contribution of the tangential lubrication corrections to the shear stress is dominant when φv surpasses 30%. For φv > 35%, increasing shear-thickening is seen with increasing φv. Following a shear reversal, the number of clusters temporarily increases and then decreases to a stable value over the same time scale as the development of the wall shear stress (and apparent viscosity). Simulations with several step changes in the shear rate show the effects of the previous shear history on the viscosity of the suspension.

Peer review status:UNDER REVIEW

25 Aug 2020Submitted to AIChE Journal
10 Sep 2020Assigned to Editor
10 Sep 2020Submission Checks Completed
19 Sep 2020Reviewer(s) Assigned