An Eulerian-Lagrangian Approach for Incompressible Fluids: Local Theory

We present a local existence result for the three dimensional incompressible Euler equations. The solution is constructed using a formulation of the equations as an active vector system in Eulerian coordinates. The formulation employs the inverse of the Lagrangian path map (the "back-to-labels" map) and its Eulerian gradient. We express sufficient conditions for regularity in terms of this gradient.