Robust Delaunay graph based mesh movement for adjoint mesh sensitivity

Surface mesh sensitivity in the discrete adjoint framework is efficiently computed using the Delaunay graph method. The method results in an explicit algebraic map between the volume and surface mesh for which the solution of the linear mesh-adjoint system, generally associated with any implicit mesh movement, is not required. This method is used for the computation of the metric term sensitivity as well as a mesh movement. This requires a careful Delaunay decomposition of the computation domain. A new formulation of the Delaunay mesh movement is presented in order to improve the decomposition of the computational domain.