BULK VISCOSITY IN RELAXING MEDIA

Two approaches for the calculation of an accoustical property of relax ing media, namely the bulk viscosity, are analysed. One of them is the thermodynamic relaxation theory and another one is the analysis of th e statistical expression for the bulk viscosity. In the frame of the s tatistical method the system of hydrodynamic equations is constructed for relaxing media. It is shown that the discrepancy between the therm odynamic and statistical approaches is connected with the influence of momentum on relaxational processes which is not contained in the ther modynamic method.