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A benchmark study on the efficiency of unconstrained optimization algorithms in 2D-aerodynamic shape design

 
: Vorspel, L.; Schramm, M.; Stoevesandt, B.; Brunold, L.; Bünner, M.

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Cogent Engineering 4 (2017), Art. 1354509, 19 pp.
ISSN: 2331-1916
English
Journal Article, Electronic Publication
Fraunhofer IWES ()

Abstract
Optimization algorithms are used in various engineering applications to identify optimal shapes. We benchmark several unconstrained optimization algorithms (Nelder-Mead, Quasi-Newton, steepest descent) under variation of gradient estimation schemes (adjoint approach, finite differences). Flow fields are computed by solving the Reynolds-Averaged Navier-Stokes equations using the open source computational fluid dynamics code OpenFOAM. Design variables vary from N = 2 to N = 364. The efficiency of the optimization algorithms are benchmarked in terms of computation time, applicability and ease of use. Results for lift optimizations are presented for airfoils at a Reynolds number of 50,000. As a result, we find for a small number of design variables N 5 or less, the computational efficiency of all optimization algorithms to be similar, while the ease of use of the Nelder-Mead algorithm makes it a perfect choice. For intermediate and large number of design variables, gradient-based algorithms with gradient estimation through the solution of adjoint equations are unbeaten.

: http://publica.fraunhofer.de/documents/N-458774.html