Numerical Study of the Optimization of Separation Control

Carnarius, Angelo; Günther, Bert; Thiele, Frank; Wachsmuth, Daniel; Tröltzsch, Fredi; Reyes, Juan C.

doi:10.2514/6.2007-58

Cited by 12 publications

(11 citation statements)

References 9 publications

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“…Broadly, we can classify the adjoint approaches into continuous and discrete adjoint methods. In the continuous adjoint method [12,13], one first derives the optimality system from the continuous optimization problem and the resulting adjoint partial differential equations (PDEs) are then discretised and solved using numerical methods. Although being computationally efficient, development of continuous adjoint flow solvers requires much effort and their maintenance becomes a problem as the underlying nonlinear flow solvers are subject to continuous modifications, e.g., new boundary conditions, new turbulence models etc.…”

Section: Introductionmentioning

confidence: 99%

A Two-Level Hybrid Approach for Optimal Active Flow Control on a Three-Element Airfoil

Nemili¹,

Özkaya²,

Gauger³

et al. 2016

Proceedings of the VII European Congress on Computational Methods in Applied Sciences and Engineering (ECCOMAS Congress 2016)

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Abstract. In this paper we present a two-level approach that combines an adjoint-based gradient search method with an evolutionary algorithm for optimal active flow control. The suggested method effectively combines the advantages of both approaches and achieves a good compromise between the computational effort and the degree of freedom used in optimization. In the first level, a global optimization is performed with few design parameters using an evolutionary algorithm. In the second level, the global optimal solution from the first level is taken as the initial setting for the adjoint based local optimization using a large number of design parameters. The unsteady discrete adjoint solver required for the second level is developed based on Algorithmic Differentiation techniques for the unsteady incompressible flowsgoverned by Unsteady Reynolds-Averaged Navier Stokes (URANS) equations. In this way, the discrete adjoint solver is robust and has exactly the same functionality with the underlying URANS flow solver. The applicability of the two-level method is demonstrated by finding the optimal parameters of the active flow control mechanism on a three element airfoil configuration at a Reynolds number of Re = 10 6 and an angle of attack of AoA = 6 • . Numerical results have shown that the hybrid approach completely suppressed the separation and very significantly increased the mean-lift coefficient by 67% compared to the un-actuated baseline flow.

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Section: Introductionmentioning

confidence: 99%

A Two-Level Hybrid Approach for Optimal Active Flow Control on a Three-Element Airfoil

Nemili¹,

Özkaya²,

Gauger³

et al. 2016

Proceedings of the VII European Congress on Computational Methods in Applied Sciences and Engineering (ECCOMAS Congress 2016)

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“…At the outflow boundary Γ out , we prescribe a so called "do nothing" condition: ν∂ n u − pn = 0. For more details of the configuration see the technical report [6].…”

Section: Numerical Solutionmentioning

confidence: 99%

“…[6,28,31]. Here, we have to deal with turbulence, which is simulated by a k-ω-WILCOX98 model, we refer to [37].…”

Section: Model Reductionmentioning

confidence: 99%

“…Due to the high dimension of the discretized equations, the computing times for any forward solution of the model are extremely large so that a mathematical optimization of the periodic actuation is fairly unrealistic. In [6], a generic high-lift configuration was investigated and one forward solution took about 48 hours. In the case of the SCCH configuration, the computation time was nearly twice that number.…”

Section: Model Reductionmentioning

confidence: 99%

“…The associated background of applications in fluid mechanics, active separation control, was subject of various papers written from an engineering point of view. We only mention [5,6,26,27,28,36], whose considerations are close to our setting.…”

Section: Introductionmentioning

confidence: 99%

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Optimal Boundary Control Problems Related to High-Lift Configurations

John

Noack

Schlegel

et al. 2010

Active Flow Control II

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We investigate two control problems related to the aerodynamic optimization of flows around airfoils in high-lift configurations. The first issue is the steady state maximization of lift subject to restrictions on the drag. This leads to a boundary control problem for the 2D stationary Navier-Stokes equations with constrained controls functions belonging to L 2 (Γ ) under an integral state constraint. We derive optimality conditions and treat the problem numerically by direct solution of the associated nonsmooth optimality system. The second part is based on a k-ω-WILCOX98 turbulence model. To deal with the curse of dimension, we discuss a reduced-order model by adapting a small system of ODEs to solutions computed with the full model.

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Versatile anisotropic mesh adaptation methodology applied to pure quantity of interest error estimator. Steady, laminar incompressible flow

Carrier

Deteix

Fortin

2019

Numerical Methods in Fluids

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Summary We introduce a new flexible mesh adaptation approach to efficiently compute a quantity of interest by the finite element method. Efficiently, we mean that the method provides an evaluation of that quantity up to a predetermined accuracy at a lower computational cost than other classical methods. The central pillar of the method is our scalar error estimator based on sensitivities of the quantity of interest to the residuals. These sensitivities result from the computation of a continuous adjoint problem. The mesh adaptation strategy can drive anisotropic mesh adaptation from a general scalar error contribution of each element. The full potential of our error estimator is then reached. The proposed method is validated by evaluating the lift, the drag, and the hydraulic losses on a 2D benchmark case: the flow around a cylinder at a Reynolds number of 20.

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Numerical Study of the Optimization of Separation Control

Cited by 12 publications

References 9 publications

A Two-Level Hybrid Approach for Optimal Active Flow Control on a Three-Element Airfoil

A Two-Level Hybrid Approach for Optimal Active Flow Control on a Three-Element Airfoil

Optimal Boundary Control Problems Related to High-Lift Configurations

Versatile anisotropic mesh adaptation methodology applied to pure quantity of interest error estimator. Steady, laminar incompressible flow

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