Energy trapping in a phononic crystal cavity enhanced by nonreciprocal acoustic wave transmission

Defect mode induced energy trapping at the bandgap frequency of a phononic crystal has been widely explored. Unlike this extensively used mechanism, this work reports the use of nonreciprocity in the transmission band to trap energy inside a phononic crystal cavity. Passive nonreciprocity is due to natural viscosity of the background liquid (water) and asymmetry of aluminum scatterers. The level of nonresonant energy trapping was compared for three cavities with different symmetry. Enhancement of energy trapping at a frequency of 624 kHz was observed experimentally for the cavity where nonreciprocity suppresses acoustic radiation into environment. Experimental results were further investigated and confirmed using finite element numerical analysis.

Automated summary

This study reports the use of nonreciprocity in the transmission band to trap energy inside a phononic crystal cavity, which is different from the widely used defect mode induced energy trapping mechanism. Passive nonreciprocity is achieved through the natural viscosity of the background liquid (water) and the asymmetry of aluminum scatterers. Experimental results show enhanced energy trapping at a frequency of 624 kHz when nonreciprocity suppresses acoustic radiation into the environment. Finite element numerical analysis further investigates and confirms the experimental findings.