Flows generated by divergence free vector fields with compact support
  We are concerned with the theory of existence and uniqueness of flows generated by divergence free vector fields with compact support. Hence, assuming that the velocity vector fields are measurable, bounded, and the flows in the Euclidean space are measure preserving, we show two counterexamples of uniqueness/existence for such flows. First we consider the autonomous case in dimension 3, and then, the non autonomous one in dimension 2. 
Olivier Kneuss and Wladimir Neves
math.AP