Morphology modulation and its forefront implication of a three-dimensional particulate-fluid system by weaving acoustic field

Relied on three-dimensional metamaterial-based particulate-fluid system, an acoustic weave platform increases the sound pressure amplitude by frequency bandgap peak gain (Q-factor 4.5) in acoustically regular air media system with ways that a conventional method cannot. The interesting morphology alternations of the aggregation, fluidization, and trapping for numerous expanded-polystyrene particles (1-7.5 mm) were experimentally observed by engineering acoustic field in the low-frequency range of <0.8 kHz, improving the weak phenomenon in the absence of acoustic-metamaterial design. With vertical square-waveguide arrayed uniformly 12 of Helmholtz sound sources, the platform modulates the acoustic wave-packet movement and amplifies resonantly the time-spatial Y-shape-bifurcated-aggregation 54.7°-long-short-range-attraction wave phenomenon of complex macro soft-matter particles. Through experiment coinciding with simulation and theory, the main behaviors' phenomena were accurately explained by acoustic radiation force and secondary radiation force joint with the modulated three-dimensional acoustic field. The particle fluidization and trapping occur on contrary acoustic gradient fields at 220 and 250 Hz, respectively. There exist several vertically parallel "chiral" layer thin-film-aggregation stripes of millimeter-scale particles also obviously appearing at 220 Hz, more intuitively displaying the quasi-waves' constructive and destructive interferences of mm-scale particles themselves for wave-particle duality theory. The macro wavelike character helps to conveniently modulate collectively the environmental behaviors of fly-ash.