The interaction between two close-to-touching convex acoustic subwavelength resonators

Abstract

The Minneart resonance is a low frequency resonance in which the wavelength is much larger than the size of the resonators. It is interesting to study the interaction between two adjacent bubbles when they are brought close together. Because the bubbles are usually compressible, in this paper we mainly investigate resonant modes of two general convex resonators with arbitrary shapes to extend the results of Ammari, Davies, Yu in [4], where a pair of spherical resonators are considered by using bispherical coordinates. We combine the layer potential method for Helmholtz equation in [4,5] and the elliptic theory for gradient estimates in [26,30] to calculate the capacitance coefficients for the coupled $C^{2,\alpha}$ resonators, then show the leading-order asymptotic behaviors of two different resonant modes and reveal the dependance of the resonant frequencies on their geometric properties, such as convexity, volumes and curvatures. By the way, the blow-up rates of gradient of the scattered pressure are also presented.