2019/02/24 by Wang, Wei, Zhou, Jia, Riaud, Antoine
#FOS: Physical sciences #Fluid Dynamics (physics.flu-dyn)
paper · doi:10.48550/arxiv.1902.08892
A wide variety of tilted washboard potentials based on acoustic waves, electric fields, optical patterns and so on have been applied to sort particles in microchannels. In this paper, we present a theoretical analysis of the particles trajectory in a washboard potential making a tilt angle θ with the flow. Depending on the sorting to drag force ratio ε, we identified a transition threshold ε= cos(θ) between two distinct regimes of particles motion: drift and locked modes. In drift mode, the particles follow an oscillating trajectory which slope is given by (ε2)/(2)tan(θ), while in locked mode the trajectory slope is given by 1/tan(θ). These theoretical predictions agree quantitatively well with previously published experimental data and may help in the design of high-performance microfluidic sorting devices.