Fig. 3.

Unsteady particle dynamics under oscillatory shear flow at Re = 0.3 and Wo = 0.095. Four representative values of AR are exemplified, i.e. AR = 1 (blue), 10 (black), 15 (green) and 30 (red). Particles originate at a fixed chosen initial position, i.e., and experience at least 1 full oscillatory cycle. (a) Time evolution (until deposition) of the settling velocity normalized by the mean settling velocity of an equivalent sphere. The area highlighted (i.e. dashed box) captures unsteady fluctuations in the settling velocity of the particle as a result of the particle flipping (as shown in (b)). Inset: initial location of the particle in the cross-sectional z–y plane. (b) Corresponding trajectories of the selected particles in the x–y plane normalized by the tube diameter. The area highlighted (i.e. dashed box) showcases the instantaneous orientation of a particle during flipping. (For interpretation of the references to color in this figure legend, the reader is referred to the web version of this article.)