Reduced-Order Models for Feedback Control of Transient Energy Growth

2018 ◽  
Author(s):  
Aniketh Kalur ◽  
Maziar Hemati
Keyword(s):  
Feedback Control ◽  
Reduced Order Models ◽  
Reduced Order ◽  
Energy Growth ◽  
Transient Energy

Feedback control of flow resonances using balanced reduced-order models

2011 ◽  
Vol 330 (8) ◽  
pp. 1567-1581 ◽  
Author(s):  
Simon J. Illingworth ◽  
Aimee S. Morgans ◽  
Clarence W. Rowley
Keyword(s):  
Feedback Control ◽  
Reduced Order Models ◽  
Reduced Order ◽  
Control Of Flow

scholarly journals Feedback Control for Transition Suppression in Direct Numerical Simulations of Channel Flow

Energies ◽  
2019 ◽  
Vol 12 (21) ◽  
pp. 4127
Author(s):  
Yiyang Sun ◽  
Maziar S. Hemati
Keyword(s):  
Feedback Control ◽  
Channel Flow ◽  
Initial Perturbation ◽  
Control Mechanisms ◽  
Linear Quadratic ◽  
Nonlinear Simulation ◽  
Energy Growth ◽  
Laminar To Turbulent Transition ◽  
Turbulent Transition ◽  
Transient Energy

For channel flow at subcritical Reynolds numbers ( R e < 5772 ), a laminar-to-turbulent transition can emerge due to a large transient amplification in the kinetic energy of small perturbations, resulting in an increase in drag at the walls. The objectives of the present study are three-fold: (1) to study the nonlinear effects on transient energy growth, (2) to design a feedback control strategy to prevent this subcritical transition, and (3) to examine the control mechanisms that enable transition suppression. We investigate transient energy growth of linear optimal disturbance in plane Poiseuille flow at a subcritical Reynolds number of R e = 3000 using linear analysis and nonlinear simulation. Consistent with previous studies, we observe that the amplification of the given initial perturbation is reduced when the nonlinear effect is substantial, with larger perturbations being less amplified in general. Moreover, we design linear quadratic optimal controllers to delay transition via wall-normal blowing and suction actuation at the channel walls. We demonstrate that these feedback controllers are capable of reducing transient energy growth in the linear setting. The performance of the same controllers is evaluated for nonlinear flows where a laminar-to-turbulent transition emerges without control. Nonlinear simulations reveal that the controllers can reduce transient energy growth and suppress transition. Further, we identify and characterize the underlying physical mechanisms that enable feedback control to suppress and delay laminar-to-turbulent transition.

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