Evolution of acoustic waves in heaped granular material

The propagation and structure of acoustic finite amplitude wave in heaped granular material is studied in this paper. The equations describing the evolution of arbitrary wave disturbances of finite amplitude velocity (density, or temperature) perturbations have been developed, with correction for heat transfer and momentum exchange between the phases under significantly unsteady conditions. The extreme cases of long- And short-wave interactions between phases are obtained. The resulting equations incorporate integral terms containing the amplitude of the perturbation. These formulae are valid for describing the evolution of waves at any ratio between the time of the internal process and the characteristic period of perturbation. Because of the high interaction between the skeleton and internal gas, the finite amplitude wave is largely dissipative. It will be shown that during the wave propagation, decrease of the wave amplitude with increasing distance is described by an exponential curve.