Applications of a discrete viscous adjoint method for aerodynamic shape optimisation of 3D configurations

Within the next few years, numerical shape optimisation based on high-fidelity methods is likely to play a strategic role in future aircraft design. In this context, suitable tools have to be developed for solving aerodynamic shape optimisation problems, and the adjoint approach—which allows fast and accurate evaluations of the gradients with respect to the design parameters—is proved to be very efficient to eliminate the shock on aircraft wing in transonic flow. However, few applications were presented so far considering other design problems involving 3D viscous flows. This paper describes how the adjoint approach can also help the designer to efficiently reduce the flow separation onset at wing–fuselage intersection and to optimise the slat and flap positions of a 3D high-lift configuration. On all these cases, the optimisations were successfully performed within a limited number of flow evaluations, emphasising the benefit of the adjoint approach in aircraft shape design.Aerodynamics, Wind Energy and PropulsionAerospace Engineerin

Goal oriented mesh adaptation using total derivative of aerodynamic functions with respect to mesh coordinates

International audienceIn aeronautical CFD, engineers require accurate predictions of the forces and moments but they are less concerned with flow-field accuracy. Hence, the so-called "goal oriented" mesh adaptation strategies have been introduced to get satisfactory values of functional outputs at an acceptable cost, using local node displacement and insertion of new points rather than mesh refinement guided by uniform accuracy. Most often, such methods involve the adjoint vector of the functional of interest. Our purpose is precisely to present new goal oriented mesh adaptation strategies in the framework of finite-volume schemes and a discrete adjoint method. It is based on the total derivative of the goal with respect to (w.r.t.) mesh nodes. More precisely, a projection of the goal derivative, removing all components corresponding to geometrical changes in the solid walls or the support of the output, is used to adapt the meshes either by adding nodes or by displacing current mesh nodes. The methods are assessed in the case of 2D and 3D Euler flow computations