  In this work we present a mimetic spectral element discretization for the 2D
incompressible Navier-Stokes equations that in the limit of vanishing
dissipation exactly preserves mass, kinetic energy, enstrophy and total
vorticity on unstructured grids. The essential ingredients to achieve this are:
(i) a velocity-vorticity formulation in rotational form, (ii) a sequence of
function spaces capable of exactly satisfying the divergence free nature of the
velocity field, and (iii) a conserving time integrator. Proofs for the exact
discrete conservation properties are presented together with numerical test
cases on highly irregular grids.
