Exponential growth of the vorticity gradient for the Euler equation on the torus

We prove that there are solutions to the Euler equation on the torus with C1,α vorticity and smooth except at one point such that the vorticity gradient grows in L∞ at least exponentially as t→∞. The same result is shown to hold for the vorticity Hessian and smooth solutions. Our proofs use a version of a recent result by Kiselev and Å verák [6].