6. Exponential growth of the length of Lagrangian flow map for 2D Euler
Find a solution u of 2D Euler with \sup_t \|u\|_{C^1(\mathbb{T}^2)} < \infty,
and a curve, l, of finite length such that the length of \Phi_t(l) grows exponentially in time. Here, \Phi_t is the Lagrangian flow map of u.
Cite this as: AimPL: Small scale dynamics in incompressible fluid flows, available at http://aimpl.org/smallscalefluid.