Control of Instabilities in an Unswept Wing Boundary Layer

Dadfar, Reza; Hanifi, Ardeshir; Henningson, Dan S.

doi:10.2514/1.j056415

Cited by 10 publications

(2 citation statements)

References 37 publications

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“…For the numerical flux at the solution domain boundary, where there is no adjacent element, a ghost state Qgh is introduced instead of the external state so that we have f = f( Qgh , Qint ). (7) In the standard use of a Riemann boundary condition the external or ghost state is independent of the interior state and the solution of the Riemann solver will provide a known boundary state Qb , i.e.…”

Section: Linearized Dg Approximation For 1d Euler Equationsmentioning

confidence: 99%

Stable, Entropy-Pressure Compatible Subsonic Riemann Boundary Condition for Embedded Dg Compressible Flow Simulations

Lyu

Chen²,

Du³

et al. 2022

SSRN Journal

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Section: Linearized Dg Approximation For 1d Euler Equationsmentioning

confidence: 99%

Stable, Entropy-Pressure Compatible Subsonic Riemann Boundary Condition for Embedded Dg Compressible Flow Simulations

Lyu

Chen²,

Du³

et al. 2022

SSRN Journal

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“…Surface temperature 14,15,46,47 , plasma actuators [48][49][50] and surface compliance 51,52 are just some of the methods that have been utilised as a means of controlling transition in boundary layers. Dynamic wall modification was utilised experimentally by Amitay et al 53 to excite and control TS disturbances on a flat plate.…”

Section: Introductionmentioning

confidence: 99%

Optimizing control of stationary cross-flow vortices excited by surface roughness

Thomas

Mughal

2022

Physics of Fluids

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Stationary cross-flow vortices are excited within the swept Hiemenz boundary layer via surface roughness and actively controlled using an optimally configured control device. Control is modelled using localised wall motion, but in practice the optimisation strategy could be applied to other laminar flow control technologies. A sensor-control iterative procedure, based on solutions of the forward and adjoint linearised Navier--Stokes equations, is applied to both feedforward and feedback loop systems. The former strategy only allows the control settings to be configured once, while the latter approach permits the repeated reoptimisation of the control device. Surface roughness establishes a stationary cross-flow disturbance with a pre-defined set of flow conditions, but an unknown amplitude and phase. A sensor measures the local amplitude of the perturbation and relays the information to the control mechanism. Solutions of the adjoint linearised Navier--Stokes equations are coupled with the sensor measurements to configure and optimise the control mechanism, and establish an anti-phase wave that brings about destructive wave interference. The amplitude of the stationary cross-flow instability is reduced by an order $10^3$ for the feedforward system, while amplitude reductions of the order $10^3$ per iteration and $10^8$ overall are realisable for the feedback modelling approach. Similar levels of flow control are realisable for a multiple controller configuration. However, stationary cross-flow disturbances could not be eliminated indefinitely. Inevitably, the cross-flow instability started to grow again, albeit at a considerably lower magnitude. The analysis is extended to include the effects of systematic error in the sensors measuring capability.

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Stable, entropy-pressure compatible subsonic Riemann boundary condition for embedded DG compressible flow simulations

Lyu

Chen

et al. 2023

Journal of Computational Physics

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Control of Instabilities in an Unswept Wing Boundary Layer

Cited by 10 publications

References 37 publications

Stable, Entropy-Pressure Compatible Subsonic Riemann Boundary Condition for Embedded Dg Compressible Flow Simulations

Stable, Entropy-Pressure Compatible Subsonic Riemann Boundary Condition for Embedded Dg Compressible Flow Simulations

Optimizing control of stationary cross-flow vortices excited by surface roughness

Stable, entropy-pressure compatible subsonic Riemann boundary condition for embedded DG compressible flow simulations

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