Optimal Control of Unsteady Flows Using Discrete Adjoints

Nemili, Anil; Gauger, Nicolas R.; Thiele, Frank

doi:10.2514/6.2011-3720

Cited by 14 publications

(12 citation statements)

References 20 publications

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Section: Discussionmentioning

confidence: 99%

“…A good discussion of the two AD modes along with checkpointing techniques can be found in. 19 A quasi-Newton optimizer in which an estimate of the inverse Hessian based on the BFGS (Broyden-FletcherGoldfarb-Shanno) rank-two update formula is used to compute a search direction. 20 The step size is determined using a line search, which enforces the strong Wolfe conditions.…”

Section: Iic Optimization Frameworkmentioning

confidence: 99%

See 1 more Smart Citation

Adjoint-based Trailing-Edge Noise Minimization using Porous Material

Zhou

Gauger

Koh

et al. 2014

20th AIAA/CEAS Aeroacoustics Conference

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In this paper, we present a discrete adjoint-based optimization framework to obtain the optimal distribution of the porous material over the trailing edge of a 3-D flat plate. The near-body strength of the noise source generated by the unsteady turbulent flow field is computed using a high-fidelity large-eddy simulation (LES). The acoustic signal thus generated is then propagated to the far-field using the acoustic perturbation equations (APE). The design gradients are computed using the forward and reverse modes of automatic differentiation (AD). The increase of memory requirement in the reverse mode AD is alleviated by checkpointing. By optimally controlling the material porosity and permeability, it is possible to minimize the turbulence intensity responsible for noise generation at the trailing edge and thus significantly reduce the radiated noise. We demonstrate, using a simple geometry as a first step, the efficacy of the discrete adjoint method in achieving minimum-noise design via optimal distribution of porous media, with future applications to aircraft high-lift devices.

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Section: Discussionmentioning

confidence: 99%

Section: Iic Optimization Frameworkmentioning

confidence: 99%

Adjoint-based Trailing-Edge Noise Minimization using Porous Material

Zhou

Gauger

Koh

et al. 2014

20th AIAA/CEAS Aeroacoustics Conference

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“…For a high-fidelity setup with millions of grid nodes explored in current work, this presents an impossible task for the reverse mode AD due to the memory overhead and can only be accomplished using advanced AD techniques such as reverse accumulation and checkpointing. 19 When the nearbody turbulence intensity measure is minimized, the design shows only marginal reduction in overall sound pressure level, even though the vorticity magnitude and the turbulence kinetic energy are both minimized in the wake region. However, when the objective function is changed to the root-mean-square of the pressure fluctuation at different off-body observation locations, the noise reduction is significant -12dB in the normal direction and up to 18dB in the upstream direction.…”

Section: Optimization Windowmentioning

confidence: 98%

On the Adjoint-based Control of Trailing-Edge Turbulence and Noise Minimization via Porous Material

Zhou

Gauger

Koh

et al. 2015

21st AIAA/CEAS Aeroacoustics Conference

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In this paper, we present a discrete adjoint-based optimization framework to obtain the optimal distribution of the porous material over the trailing edge of a 3-D flat plate. The near-body strength of the noise source generated by the unsteady turbulent flow field is computed using a high-fidelity large-eddy simulation (LES). The acoustic signal thus generated is then propagated to the far-field using the acoustic perturbation equations (APE). The design gradients are computed using the forward and reverse modes of algorithmic differentiation (AD). The increase of memory requirement in the reverse mode AD is alleviated by checkpointing. By optimally controlling the material porosity and permeability, it is possible to minimize the turbulence intensity responsible for noise generation at the trailing edge and thus significantly reduce the radiated noise. The optimal porous trailing-edge design achieves a noise reduction of up to 18dB.

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“…Papadimitriou dpapadim@uth.gr In aerodynamics, the conventional adjoint approach to the optimisation of unsteady flows, based on the timeaccurate adjoint equations, has been applied to the drag minimisation of airfoils with deforming meshes (Mani and Mavriplis 2008;Mavriplis 2008), the optimisation of active unsteady flow control based on jets (Nielsen and Jones 2011;Nemili et al 2011), optimisation of rotors (Nielsen, Lee-Rausch, and Jones 2010), aeroelastic optimisation (Mani and Mavriplis 2009), flutter suppression (Palaniappan et al 2011;Zhang et al 2013), error estimation (Krakos and Darmofal 2010), uncertainty quantification (Wang 2008), etc.…”

Section: Introductionmentioning

confidence: 99%

A two-step back–forth algorithm for the solution of the unsteady adjoint equations

Papadimitriou

2016

International Journal of Computational Fluid Dynamics

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A new algorithm for the solution of the unsteady adjoint equations is proposed in this article, aiming at overcoming the excessive computational cost and memory requirements of the conventional adjoint approach for the optimisation of unsteady problems in computational mechanics. The total cost is equal to four times the cost of the unsteady state solution, which is twice the cost of the conventional backward-in-time adjoint calculation but the memory requirements are very small, equivalent to those of a steady-state problem, while stability is acceptable. The proposed algorithm is validated in the case of the 1D unsteady Burgers equation with non-smooth source terms.

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Optimal Control of Unsteady Flows Using Discrete Adjoints

Cited by 14 publications

References 20 publications

Adjoint-based Trailing-Edge Noise Minimization using Porous Material

Adjoint-based Trailing-Edge Noise Minimization using Porous Material

On the Adjoint-based Control of Trailing-Edge Turbulence and Noise Minimization via Porous Material

A two-step back–forth algorithm for the solution of the unsteady adjoint equations

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