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Sensitivity computations by automatic differentiation of a CFD code based on spectral differences

Cardesa, José I. and Airiau, Christophe Sensitivity computations by automatic differentiation of a CFD code based on spectral differences. (2019) In: 24ème congrès français de Mécanique, 26 August 2019 - 30 August 2019 (Brest, France).

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Abstract

Control and optimization in fluid mechanics rely on the computation of flow sensitivities. We compute flow sensitivities by modifying a high-order computational fluid dynamics code which is spatiallydiscretized with spectral differences. Our approach is fully discrete, relying on algorithmic differentiation of the original source code. We obtain two transformed codes by using TAPENADE, one for each differentiation mode : tangent and adjoint. Both codes compute sensitivities in an unsteady test case of two-dimensional incompressible flow over a periodic cube with an initial double-shear profile. We find that the sensitivities from both differentiation modes agree to within machine accuracy, and compare well with those approximated by finite difference (FD) computations. We compare and discuss execution times, which in our case of a single-input/single-output problem are naturally in favor of the tangent code. The latter even outperforms the FD computation time.

Item Type:Conference or Workshop Item (Paper)
HAL Id:hal-02617419
Audience (conference):National conference proceedings
Uncontrolled Keywords:
Institution:French research institutions > Centre National de la Recherche Scientifique - CNRS (FRANCE)
Université de Toulouse > Institut National Polytechnique de Toulouse - Toulouse INP (FRANCE)
Université de Toulouse > Université Toulouse III - Paul Sabatier - UT3 (FRANCE)
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Funders:
RTRA STAE, Toulouse - European Union’s Seventh Framework Programme
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Deposited On:25 May 2020 09:28

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