DNS and LES of estimation and control of transition in boundary layers subject to free-stream turbulence

Monokrousos, Antonios; Brandt, Luca; Schlatter, Philipp; Henningson, Dan S.

doi:10.1016/j.ijheatfluidflow.2008.03.009

Cited by 41 publications

(40 citation statements)

References 48 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The parametric study performed confirms that transition is enhanced when increasing the turbulence intensity and the integral length scale of the turbulence, that is when reducing its decay rate downstream, see also Ref. 7. The turbulence level in the simulation matching the experiment is considerable higher than the one in the experiments.…”

Section: Iva Matching Of the Disturbance Growth Without Controlsupporting

confidence: 74%

See 1 more Smart Citation

Feedback Control of Boundary Layer Bypass Transition: Experimental and Numerical Progress

Lundell¹,

Monokrousos²,

Brandt³

2009

47th AIAA Aerospace Sciences Meeting Including the New Horizons Forum and Aerospace Exposition

Self Cite

View full text Add to dashboard Cite

Experimental and numerical work at the Linné FLOW Centre on active control of transition induced by free-stream turbulence is reviewed and two extensions to previous work are reported. Previously, an experimental setup with upstream sensors and downstream actuators has been built. It has been demonstrated that an ad-hoc control algorithm is able to give a considerable attenuation of the disturbance amplitude downstream of the actuators. Furthermore, large-eddy simulations (LES) of optimal feedback control have been performed for a similar flow configuration and disturbance attenuation as well as transition delay have been obtained. Two extensions are made. First, an effort is made to match the disturbance behavior in the experimental flow case and in the LES. Control is applied in simulations of the matched system aiming at approaching the type of actuation used in the experiments (localized suction). The control law is still computed as optimal feedback of the linear system. As the actuation ability approaches the experiments (where much simpler controllers were used), so does the control effect. Second, system identification (SI) is applied to the experimental data and a more efficient controller is designed. It is made plausible that controllers designed by SI can give considerable improvements in the disturbance attenuation. Implications for future work in the area of active control are discussed.

show abstract

Section: Iva Matching Of the Disturbance Growth Without Controlsupporting

confidence: 74%

“…7 The aim is to introduce the method and approach pursued. Bypass transition induced by high levels of freestream turbulence above a boundary layer was simulated using direct numerical simulations (DNS)…”

Section: Review Of Numerical Simulations Of Feedback Controlmentioning

confidence: 99%

Feedback Control of Boundary Layer Bypass Transition: Experimental and Numerical Progress

Lundell¹,

Monokrousos²,

Brandt³

2009

47th AIAA Aerospace Sciences Meeting Including the New Horizons Forum and Aerospace Exposition

Self Cite

View full text Add to dashboard Cite

show abstract

“…This procedure has been used for plane channel flow by Högberg, Bewley & Henningson (2003) and later extended for weakly spatially developing flows by Chevalier et al (2007a) and Monokrousos et al (2008). Apart for the limit imposed by the hypothesis of spatial invariance of the system, a drawback of this methodology is the necessity of introducing a distributed system of sensors and actuators.…”

Section: Full-dimensional Controllers and Flow Controlmentioning

confidence: 99%

Riccati-less approach for optimal control and estimation: an application to two-dimensional boundary layers

et al. 2013

Self Cite

View full text Add to dashboard Cite

The control of Tollmien-Schlichting (TS) in a 2D boundary layer is analysed by using numerical simulation. Full-dimensional optimal controllers are used in combination with a set-up of spatially localised inputs (actuators and disturbance) and outputs (sensors). The Adjoint of the Direct-Adjoint (ADA) algorithm, recently proposed by Pralits & Luchini (2010), is used to efficiently compute the Linear Quadratic Regulator (LQR) controller; the method is iterative and allows to by-pass the solution of the corresponding Riccati equation, unfeasible for high-dimensional systems. We show that an analogous iteration can be cast for the estimation problem; the dual algorithm is referred to as Adjoint of the Adjoint-Direct (AAD). By combining the solutions of the estimation and control problem, a full dimensional, model-free, Linear Gaussian Quadratic (LQG) controllers are obtained and used for the attenuation of the disturbances arising in the boundary layer flow. Model-free, full dimensional controllers turn out to be an excellent benchmark for evaluating the performance of the optimal control/estimation design based on open-loop model reduction. We show the conditions under which the two strategies are in perfect agreement by focusing on the issues arising when feedback configurations are considered. An analysis of the finite amplitude cases is also carried out addressing the limitations of the optimal controllers, the role of the estimation and the robustness to the nonlinearities arising in the flow of the control design

show abstract

“…In these studies-due to the compact support of the feedback kernels-a small spanwise strip of the flat plate could be used for sensing and actuation. The true significance of damping small-amplitude perturbations for transition delay was shown in direct numerical simulations and large-eddy simulations by Monokrousos et al [13] of the flat plate in the presence of free-stream turbulence (Tu = 4.7%). As shown in figure 5, the decentralized feedback controller, which uses only small strips of the flat plate for sensing and control, is able to delay the entire transition process by damping the linear growth of perturbations, despite the presence of strong nonlinear effects.…”

Section: (B) Decentralized Approachmentioning

confidence: 83%

Transition delay using control theory

Bagheri

Henningson

2011

Phil. Trans. R. Soc. A.

View full text Add to dashboard Cite

This review gives an account of recent research efforts to use feedback control for the delay of laminar-turbulent transition in wall-bounded shear flows. The emphasis is on reducing the growth of small-amplitude disturbances in the boundary layer using numerical simulations and a linear control approach. Starting with the application of classical control theory to two-dimensional perturbations developing in spatially invariant flows, flow control based on control theory has progressed towards more realistic three-dimensional, spatially inhomogeneous flow configurations with localized sensing/actuation. The development of low-dimensional models of the Navier-Stokes equations has played a key role in this progress. Moreover, shortcomings and future challenges, as well as recent experimental advances in this multi-disciplinary field, are discussed.

show abstract

DNS and LES of estimation and control of transition in boundary layers subject to free-stream turbulence

Cited by 41 publications

References 48 publications

Feedback Control of Boundary Layer Bypass Transition: Experimental and Numerical Progress

Feedback Control of Boundary Layer Bypass Transition: Experimental and Numerical Progress

Riccati-less approach for optimal control and estimation: an application to two-dimensional boundary layers

Transition delay using control theory

Contact Info

Product

Resources

About