Fig. 4: Experimental and numerical observation.
From: Acoustic lattice resonances and generalised Rayleigh–Bloch waves
a, b Normalised experimental and numerical Fourier spectra respectively from line scans for the configuration of 80 rods with r/a1 = 0.15. The mode above the cut-off is predominant, as predicted in Figs. 1c and 2b. c, d Show similar spectra but for the ratio r/a2 = 0.35—no mode above the cut-off is supported. Insets show logarithm of the Fourier spectra in the regions highlighted by the dashed rectangles, where the peeling of the mode off the sound-line is more visible. Overlaid points are from the eigenfrequency study (Fig. 2). Schematics show the unit strips.
