New technologies for advanced three-dimensional optimum shape design in aeronautics

The analysis of complex flows around realistic aircraft geometries is becom ing more and more predictive. In order to obtain this result, the complexit y of flow analysis codes has been constantly increasing, involving more ref ined fluid models and sophisticated numerical methods. These codes can only run on top computers, exhausting their memory and CPU capabilities. It is, therefore, difficult to introduce best analysis codes in a shape optimizat ion loop: most previous works in the optimum shape design field used only s implified analysis codes. Moreover, as the most popular optimization method s are the gradient-based ones, the more complex the flow solver, the more d ifficult it is to compute the sensitivity code. However, emerging technolog ies are contributing to make such an ambitious project, of including a stat e-of-the-art flow analysis code into an optimisation loop, feasible. Among those technologies, there are three important issues that this paper wishes to address: shape parametrization, automated differentiation and parallel computing. Shape parametrization allows faster optimization by reducing the number of design variable; in this work, it relies on a hierarchical multi level approach. The sensitivity code can be obtained using automated differ entiation. The automated approach is based on software manipulation tools, which allow the differentiation to be quick and the resulting differentiate d code to be rather fast and reliable. In addition, the parallel algorithms implemented in this work allow the resulting optimization software to run on increasingly larger geometries. Copyright (C) 1999 John Wiley & Sons, Lt d.