The scattering of sound by objects with dynamic deformations.

In this article, a sonic scattering problem of arbitrarily shaped, time-varying rigid surfaces is analytically solved by exploiting perturbation theory. The results demonstrate multi-frequency scattering characteristics resulting from a single moving object and the nonreciprocity from spinning components. The proposed approach is numerically verified, from audio through to ultrasonic frequencies, by full-wave simulation based on the finite-element method. This numerical simulation also validates the non-reciprocal phenomenon in such systems. In addition, the theory for multiple Floquet scattering of sound is built, which lays the foundation for advanced studies relevant to Floquet phononic crystals and novel time-varying sonic devices. [ABSTRACT FROM AUTHOR]