Compressional Waves in Media with Complex Viscosity

Abstract

The author recently suggested the introduction of a complex viscosity in the theory of vibrations of materials which lie between the purely crystalline and the liquid state. This conception is utilized here in the theory of compressional waves in an infinite medium. One of the conclusions, namely, the decrease of the attenuation factor with increasing frequency, is in agreement with observations. Another conclusion is an increase of the propagation velocity with frequency. Both changes occur in the neighborhood of a certain characteristic frequency, given by the reciprocal of the so‐called relaxation constant. Below this frequency range the material vibrates like a liquid; above this range like a crystal.