Hydrodynamics of magnetic and dielectric fluids in interaction with the electromagnetic field

The hydrodynamics of polar fluids and suspensions in interaction with the electromagnetic field is studied in the framework of irreversible thermodynamics. It is shown that the approach developed earlier by de Groot and Mazur can be extended to include intrinsic rotation and a decomposition of polarization and magnetization into slow and fast parts. An expression for the entropy production is derived which leads to phenomenological relaxation equations. For incompressible fluids these reduce to relaxation equations postulated in the literature. If it is assumed that intrinsic rotation decays much faster than the other variables, then a simplified description is possible in which the intrinsic angular momentum does not occur. Several proposed expressions for electromagnetic stress tensor and force density are discussed and shown to be inadequate.