DIELECTRIC-RELAXATION IN POLAR AND VISCOELASTIC FLUIDS WITH INTERNAL-ROTATION

Using the formalism of extended irreversible thermodynamics we derive the generalized constitutive equations for the polarization vector and the symmetric and antisymmetric parts of the total stress tensors (the sum of the Maxwell and viscous stress tensors) of a viscoelastic polar fluid. The analysis of these equations shows several interesting features for a permanent dipolar system. The diffusive transport of polarization charge and the diffusion of the transverse polarization component are two elementary physical processes in terms of which complex cases of dielectric relaxation can be described, taking into account both translational and rotational motions of the dipolar particles in a viscoelastic fluid. The calculations for several cases of the complex dielectric susceptibility are presented. In these results, the coupling between polarization and hydrodynamics predicts several modes of dielectric energy dissipation. These various channels are due to the intimate coupling between different degrees of freedom, taken into account by the constitutive equations. The calculation of the complex shear and rotational viscosities complete the presentation.