Unsteady 2-D and axisymmetric viscous cavitating flows are modeled numerically by solution of the two-phase laminar Navier-Stokes equations formulated with a homogeneous fluid model. Results are obtained for large L/D slots with chamfered orifices of various dimensions and are compared to recent experiments. The model is used to study the effects of orifice size, pressure drop, and the site density (a free variable arising irt the homogeneous fluid formulation related to the number of nucleation sites in the flow field) on the length and periodicity of the cavitation region. Increases in the pressure drop across the orifice or the site density has the tendency to increase the extent of cavitation and decrease the frequency of oscillation about the average length of the cavitating region.