Effects of volume fraction and particle shape on the rheological properties of oblate spheroid suspensions

Abstract

Coupled lattice Boltzmann and discrete element methods were employed to investigate the rheological properties of oblate spheroid suspensions in a Newtonian fluid. The volume fraction of the particles is varied, along with the particle aspect ratio. As the particle shape is varied from sphere to oblate, we observe an increase of the relative viscosity, as well as an increase of the particle contacts and the contact distance. The more oblate particles in denser suspensions are observed to reorient systematically subject to the shear flow.We recast the viscosity data using the Krieger-Dougherty formula and report the modified Einstein coefficients.

Evolution of Rayleigh−Taylor instability at the interface between a granular suspension and a clear fluid

“…The numerical algorithm is implemented using an open-source package called 'OpenLB' [25][26][27] , which we recently employed to investigate particle-fluid flow problems 28,29 . In this computational framework, Navier-Stokes equations are solved for the fluid phase using the LB method (see, e.g., Krüger 30 ), and discrete particle dynamics are solved using the DE method 31 .…”

“…For the former, the particle contact model and the associated physical parameters are identical to those reported by Guo et al 28 ; for the latter, two-way momentum exchange between the solid and fluid phases is achieved by the classic 'bounce-back' approach 32 using the fluid flow field solved explicitly around each particle by the LB method. The detailed formulations of these methods are presented in Guo 33 .…”

“…The coupled LB-DE algorithm has been validated by our recent works 28,29 . In simulating single-phase plane Poiseuille flow and single particle settling in a Newtoninan or non-Newtonian fluid, we saw good agreement with the respective analytical solutions (see Appendix B of Guo et al 29 ), confirming the algorithm's capability to simulate fluid flows and fluid-particle interactions.…”

“…In simulating single-phase plane Poiseuille flow and single particle settling in a Newtoninan or non-Newtonian fluid, we saw good agreement with the respective analytical solutions (see Appendix B of Guo et al 29 ), confirming the algorithm's capability to simulate fluid flows and fluid-particle interactions. For particle-particle interactions in dense granular suspensions, we performed simulations of particle-laden plane Couette flow in Guo et al 28 The effective viscosity of the suspension (see Fig. 2 of Guo et al 28 ) exhibits the expected behaviour according to the Krieger-Dougherty formula [i.e., Eq.…”

“…For particle-particle interactions in dense granular suspensions, we performed simulations of particle-laden plane Couette flow in Guo et al 28 The effective viscosity of the suspension (see Fig. 2 of Guo et al 28 ) exhibits the expected behaviour according to the Krieger-Dougherty formula [i.e., Eq. ( 2)].…”