This paper presents the development of a quasi-homogeneous isenthalpic cavitation flow model, suitably modified to account for thermal cavitation, and its application to the study of plane journal bearings with constant eccentricity. The proposed model treats the cavitating and noncavitating portions of the fluid in a unified manner with the aim of avoiding the use of matching conditions at the phase interface, whose accuracy is questionable in the presence of significant inertial and/or unsteady effects. A non-linear analysis which accounts for the inertia of the lubricant is used to determine the reaction forces caused by the shaft eccentricity both in the viscosity-dominated regime and at intermediate values of the Reynolds number, where the inertia of the lubricant is no longer negligible. The classical iteration method for the Reynolds lubrication equation (Muster and Sternlicht, 1965; Mori and Mori, 1991; Reinhardt and Lund, 1975) has been extended to the two-phase flow case in order to account for flow acceleration effects in the presence of cavitation. Comparison with available experimental data are shown in a number of representative cases, in order to illustrate the validity and the capabilities of the proposed model for the analysis of cavitating flows in journal bearings, in view of its extension to the case of whirling loads and eccentricities.