FIG. 4.

(a) Experimental image of near-field particle alignment adjacent to a PDMS wall under the action of a travelling SAW in X (Multimedia view). Simulated normalised pressure fields, ⟨P⟩, in the XY and XZ planes of an equivalent liquid channel (measuring 8 λ_SAW in X, 7 λ_SAW in Y, and 20 μm in Z; scale bars are one acoustic wavelength) are obtained using (b) our spherical wave model (SWM) and (c) FEM. Simulation results are shown in the XY plane at a height of 5 μm above the substrate, corresponding to the height of pressure nodes in the channel. The spacings between adjacent nodes are plotted in (d). Multimedia view: https://doi.org/10.1063/1.5021117.1Download video file ^{(5.9MB, avi)} DOI: 10.1063/1.5021117.1