The $h$-principle and the equations of fluid dynamics
  In this note we survey some recent results for the Euler equations in compressible and incompressible fluid dynamics. The main point of all these theorems is the surprising fact that a suitable variant of Gromov's $h$-principle holds in several cases. 
Camillo De Lellis, and L\'aszl\'o Sz\'ekelyhidi Jr
math.AP math.DG