Crossover in the Anderson transition: Acoustic localization with a flow

Acoustic waves propagating in a sufficiently disordered medium are localized because of multiple elastic scattering. The presence of a uniform flow in the medium breaks time-reversal invariance and changes the mechanism of localization. A field theory incorporating the crossover induced by a flow field is described and the crossover behavior of the localization length is calculated. An experimental realization of this phenomenon is proposed using third sound in a superfluid film on a rough substrate with a uniform superfluid flow