A preconditioned, homogenous, multiphase, Reynolds Averaged Navier-Stokes model with mass transfer is presented. Liquid, vapor, and noncondensable gas phases are included. The model is preconditioned in order to obtain good convergence and accuracy regardless of phasic density ratio or flow velocity. Both incompressible and finite-acoustic-speed models are presented. Engineering relevant validative and demonstrative unsteady and transient two and three-dimensional results are given. Transients due to unsteady cavitating flow including shock waves are captured. In modeling axisymmetric cavitators at zero angle-of-attack with 3-D unsteady RANS, significant asymmetric flow features are obtained. In comparison with axisymmetric unsteady RANS, capture of these features leads to improved agreement with experimental data. Conditions when such modeling is not necessary are also demonstrated and identified
