Videos

Weak and measure-valued solutions of the Euler equations

February 26, 2010
Abstract
Keywords: weak solutions, turbulence, h-principle Abstract: In 1993 V. Scheffer produced a nontrivial weak solution of the 2D incompressible Euler equations with compact support in space-time. Subsequently A.Shnirelman gave different constructions for solutions with (i) compact support in time and (ii) strictly decreasing energy. Such "wild" solutions seemingly contradict the idea of an evolution equation. In this talk we will discuss a recent approach to such constructions in joint work with Camillo De Lellis. Moreover, we show that the underlying phenomenon has a striking similarity to the h-principle, a well known phenomenon of flexibility in underdetermined geometric problems. In such situations the underlying PDE seems to represent no constraint at all, the only restrictions on the space of solutions come from topology. We look at the Euler equations in this light and show that there are indeed nontrivial restrictions arising from the initial data.