Numerical investigation of particle cloud sedimentation in power-law shear-thinning fluids for moderate Reynolds number

A series of numerical simulations are performed for the sedimentation process of a particle cloud in shear-thinning fluids using lattice Boltzmann and discrete element methods. The initial particle concentration, c(0), and the power-law index of the fluid, n, and Reynolds number, Re, are varied in these simulations. For 1.0 <= Re <= 10.9, the particle cloud size grows in the longitudinal direction as the cloud settles, leading to reduced particle concentration and a quasi-steady settling velocity, (w) over bar (infinity). The velocity ratio, (w) over bar (infinity)/w(infinity), where w(infinity) is the corresponding single-particle terminal velocity, is found to decrease with both n and Re. This velocity ratio is only weakly dependent on the initial concentration (0.05 <= c(0) <= 0.20) due to particle dispersion. For 0.071 <= Re <= 1.0, the cloud loses its initial shape and disintegrates while settling, with particles escaping from the cloud due to differential particle settling velocities. (C) 2021 Elsevier Ltd. All rights reserved.

Automated summary

Numerical simulations were conducted for particle cloud sedimentation in shear-thinning fluids, revealing that the settling velocity ratio decreases with increasing power-law index and Reynolds number, while showing weak dependence on initial concentration.