Acoustic resonances in a confined set of macroscopic disks

We study in this work a system of granular disks enclosed in a rectangular region. Granular disks are arranged, at high particle density, in a hexagonal lattice. Specifically, we are interested in the conditions for mechanical signal transmission. Two different potentials are considered. Our results are obtained by means of soft disks computer simulations. We analytically determine the eigenfrequencies spectra of the system from the corresponding Hessian matrix. Alternatively, the eigenfrequencies can also be obtained from the time evolution of molecular dynamics simulations. Previous works have shown that mechanical signal transmission in granular matter can be used to develop acoustic switches. Our results reveal that the working range of the granular switch changes dramatically for different interaction models. In particular, strong anisotropies in signal transmission may appear for certain interparticle forces.