Acoustic Pulling with a Single Incident Plane Wave

The rapid development of active acoustic metamaterials provides an alternative degree of freedom to manipulate scattering fields and acoustic radiation forces. With the multipole expansion method, acoustic radiation forces can be expanded in a series of coupling between adjacent pairs of scattering-field coefficients. Here, systems from two dimensional to one dimensional are explicitly considered. When shining a single acoustic plane wave, a necessary requirement to achieve negative force is that the particle has to be sufficiently active. A criterion of achieving the most negative or positive force by tuning the adjacent terms "in phase"or "out of phase"is derived. Thus, with the required scattering coefficients, the effective density and modulus corresponding to the largest pulling-pushing forces can be retrieved directly and function as a guide in the design of active metamaterials in one-dimensional systems. Our study can bridge the theoretical requirements of radiation force with the practical design of metamaterials.