Anisotropic Grid Adaptation for Multiple Aerodynamic Outputs

Abstract

Anisotropic grid–adaptive strategies are presented for viscous flow simulations in which the accurate prediction of multiple aerodynamic outputs (such as the lift, drag, and moment coefficients) is required from a single adaptive solution. The underlying adaptive procedure is based on a merging of adjoint error estimation and Hessian-based anisotropic grid adaptation. Airfoil test cases are presented to demonstrate the various adaptive strategies including a single element airfoil at cruise conditions and a multi-element airfoil in high-lift configuration with flow separation. Numerical results indicate that the lift, drag and moment coefficients are accurately predicted by all of the output–based strategies considered, although slightly better accuracy is obtained in the output(s) for which a particular strategy is specifically designed. Furthermore, the output-based strategies are all shown to be significantly more efficient than pure Hessian-based adaptation in terms of output accuracy for a given grid size.