A Simple Formulation of Non-Equilibrium Thermodynamics of a Polarizable Fluid

An expression of the total entropy production rate of a one-component polarizable fluid without an intrinsic angular momentum is derived from conservation laws in the Newtonian mechanics. A simple expression of the field energy-momentum four-tensor derived by Imai [J. Phys. Soc. Jpn. 60 (1991) 4100] saves us a lot of calculations, and allows us to define the heat flux and the internal energy consistently. Our derivation supposes neither small polarization nor small magnetization, and terms involving them come out symmetrically. Our result is naturally expressed in terms of the fields measured in the unique inertial frame where the fluid is relaxed to be at rest.