56 CHAPTER 6. STREAMING STUDIES
Figure 6.3: (a) Measured trajectories (thin black lines) of 0.5-m-diameter particles obtained using the
3D-APTV technique in the microchannel (gray walls) actuated at its horizontal half-wave resonance. For
selected trajectories, the particle positions are represented by dots. The particle motion is dominated by the
streaming-induced drag and follow circular trajectories. (b) Comparison between experimental, analytical,
and numerical studies of the acoustophoretic particle velocities of 0.5-m-diameter polystyrene particles
in water. The particle velocities (vectors) and their magnitude color plot ranging from 0 m/s (black)
to 63 m/s (white) in all three plots are shown in the vertical cross section of the microchannel, divided
into a pixel array consisting of 37 15 square bins of side length 10 m. The axes of the plot coincide
with the position of the channel walls. There are no free parameters in the theoretical predictions, as the
acoustic energy density was calibrated in situ based on measurements of large 5-m-diameter particles.
Figure adapted from Ref. 11 Appendix B.