Adjoint Consistency Analysis of Discontinuous Galerkin Discretizations
SIAM J. Numer. Anal. Volume 45, Issue 6, pp. 2671-2696 (2007)
http://dx.doi.org/10.1137/060665117
This paper gives a notion of consistent adjoint discretizations for DG methods. However the definition seems to be restricted to smooth solutions only. For the case of a conservation law, they show that boundary conditions of the primal problem must be appropriate for the corresponding adjoint discretization...