Cavitation versus Vortex Nucleation in a Superfluid Model

We consider a ``subcritical'' nonlinear Schr\"odinger equation as a simple model of a biphase (vapor/liquid) superfluid helium. Both cavitation and vortex nucleation might occur in such a liquid whenever the local velocity exceeds certain critical values. In our model, the critical velocity for cavitation is smaller than the one for the appearance of vortices. However, cavitation mediates vortex nucleation by a self-sustained mechanism. This effect dramatically decreases the critical speed for dissipation.