Figure 3.

Schematic diagram of the trajectories of particles of two different sizes at different forcing angles. The driving angles are (a) α < θ₁< θ₂, (b) θ₁ < α < θ₂ and (c) θ₁ < θ₂ < α, respectively. We assume that the critical angle (θ₂) of large particles is greater than the critical angle (θ₁) of small particles. The b_c and l sinα at different forcing angles were given in the schematic diagram.