Correlation function approach to bulk viscosity and sound propagation in critical mixtures

Abstract

The bulk viscosity and sound absorption in critical mixtures are studied theoretically using the general theory of anomalous transport coefficients developed in an earlier paper. The anomalous increase in the bulk viscosity near the critical point is found to be much greater than that of shear viscosity. As a natural extension of this result the anomalously large sound absorption in critical mixtures has been obtained by considering the frequency-dependent bulk viscosity. The result is found to be practically identical with the one which has been obtained by Fixman in an entirely different way and has been thought to be additional to that due to viscosities. An intuitive way of looking at our general theory is also discussed.