Aerofoil Optimisation via AD of a Multigrid Cell-Vertex Euler Flow Solver.

We report preliminary results in the use of ADIFOR 2.0 to determine aerodynamic sensitivities of a 2-D airfoil with respect to geometrical variables. Meshes are produced with a hyperbolic interpolation technique. The flow field is calculated using the cell-vertex method of Hall, which incorporates local time-stepping, mesh sequencing and multigrid. We present results and timings using both Finite Differences (FD) and Automatic Differentiation (AD). We investigate the effect of starting the perturbed calculation for FD and the derivative calculation for AD from either the current or freestream conditions and highlight the need for careful implementation of convergence criteria. We attempt to make a comparative study of AD and FD gradients in an aerofoil optimisation, using the DERA CODAS method from the perspective of DERA's eventual aim, 3D viscous optimisation of wing-body configurations.