LAUSR

Particles suspended in conduit flows at small and intermediate Reynolds numbers cluster on specific focal positions while also forming particle pairs and trains due to flow-mediated interactions. The recent introduction of oscillatory inertial microfluidics has enabled the creation of virtually infinite channels, allowing the manipulation of particles at extremely low particle Reynolds numbers (Rep ≪ 1). Here, we investigate experimentally the dynamics of formation, the robustness and the stability of particle pairs, and the precision of the inter-particle distance in an oscillatory flow field, in microchannels with a rectangular cross section. Our results indicate that the cross-sectional arrangement of the particles is fundamental in determining the characteristics of the resulting particle pair.