Figure 2.

Theoretical and experimental equilibrium velocities of undeformed spheres. (A) Size dependence of the velocity ratio, $v/u$, where v is the equilibrium velocity of the sphere and u is the peak velocity of the Poiseuille flow in the channel. Velocity ratios were obtained from the stream-function approach (solid line), or from finite-element simulations in a cylindrical channel (circle) or a square channel (square). The cylindrical channel was chosen such that the equivalent channel radius condition, $2R_{\text{eq}}=1.094\times L$ (inset), was satisfied (32). (B) Velocity measurement of polystyrene beads of different mean diameters (10.4 μm, 12.3 μm, 15.2 μm, and 19.3 μm) being flushed through a microfluidic channel with a square cross section (width $L=20$μm) using a high-precision syringe pump. The solid line depicts the solution derived from the stream-function approach. The graph contains 817 measurement points (triangles). The inset scale bars are 10 μm. To see this figure in color, go online.