A cavitation model considering the second-order derivative and bubble-bubble interaction is proposed. The bubble wall velocities are obtained by integrating the modified Rayleigh equation. The bubble-bubble interaction is measured by the coupling strength, which is modified for the hydrodynamic cavitating flows during the evaporation and decreases sharply at the cluster boundary during the condensation. The phase change rates are greatly reduced when the bubble-bubble interaction is considered, except at extremely low vapor volume fraction. Numerical results are given for the collapse of cavitation clusters and the unsteady cavitating flows around two NACA0015 hydrofoils. Comparisons are made with the experimental data and Zwart–Gerber–Belamri cavitation model.