Uniqueness and non-uniqueness in acoustic tomography of moving fluid

We consider a model time-harmonic wave equation of acoustic tomography of moving fluid in an open bounded domain in Rd, d £2, with variable sound speed c, density , fluid velocity v and absorption coefficient. We give global uniqueness results for related inverse boundary value problem for the cases of boundary measurements given for two and for three fixed frequencies. Besides,we also give a non-uniqueness result for this inverse problem for the case of boundary measurements given for all frequencies.