Figure 7

(a) Collection of \(r_p=\)10 \(\upmu \hbox {m}\) glass particles through a capillary wave excited in a ring (diameter 6 \(\hbox {mm}\)); the base here is vibrated horizontally at \(V_0=\)1 \(\hbox {V}\) and a frequency of 24 \(\hbox {Hz}\), which sets up a wave of one wavelength, as indicated in the inset. (b) Collection of \(r_p=\)10 \(\upmu \hbox {m}\) glass particles through a capillary wave excited in a ring (diameter 8 \(\hbox {mm}\)); the base here is vibrated vertically at \(V_0=\) \({3}\,\hbox {V}\) and frequency of 35 \(\hbox {Hz}\), which sets up a wave of 1.5 wavelength, as indicated in the inset. The yellow dashed lines indicate particles trapped at the water-air interface. The images in (a,b) have been altered digitally by inversion and contrast adjustment for clarity.