Abstract
The energy balance of the elastodynamic field generated by a spherical cavity in a homogeneous, isotropic, and unbounded medium is studied. The near-field waves are found to play an essential role in the energy balance, transforming static energy into wave energy and vice versa, thus displaying a surprising ability to transmit wave energy in the direction opposite to wave propagation. The occurrence of such a negative wave energy clarifies the energy balance of sources, in which the waves are associated with energy dissipation rather than radiation.
DOI:https://doi.org/10.1103/RevModPhys.66.241
©1994 American Physical Society
