Unsteady heat conduction by internal-energy waves in solids

The propagation of thermal waves at finite speed is analyzed both for processes which fulfill the local equilibrium hypothesis and for processes which do not fulfill this hypothesis. A modified form of the Cattaneo-Vernotte constitutive equation for the heat-flux-density vector is proposed. The constitutive equation does not require the definition of a thermodynamic temperature field for local nonequilibrium states and, for a homogeneous medium, relates the heat-flux-density vector to the internal-energy distribution. The proposed model is applied to investigate the propagation of axisymmetric thermal waves in an infinite solid medium. © 1997 The American Physical Society.