Suboptimal feedback control of distributed systems: Part II. Discussion of test systems and numerical results

AIChE Journal ◽  
1973 ◽  
Vol 19 (1) ◽  
pp. 129-137 ◽  
Author(s):  
J. Gregory Vermeychuk ◽  
Leon Lapidus
Keyword(s):  
Distributed Systems ◽  
Feedback Control ◽  
Numerical Results ◽  
Test Systems ◽  
Suboptimal Feedback Control

Suboptimal feedback control of vortex shedding at low Reynolds numbers

1999 ◽  
Vol 401 ◽  
pp. 123-156 ◽  
Author(s):  
CHULHONG MIN ◽  
HAECHEON CHOI
Keyword(s):  
Feedback Control ◽  
Vortex Shedding ◽  
Bluff Body ◽  
Inviscid Flow ◽  
Cylinder Surface ◽  
Control Procedure ◽  
Control Input ◽  
Flow Pressure ◽  
Cost Functionals ◽  
Suboptimal Feedback Control

The objective of this study is to develop a method of controlling vortex shedding behind a bluff body using control theory. A suboptimal feedback control procedure for local sensing and local actuation is developed and applied to the flow behind a circular cylinder. The location of sensors for feedback is limited to the cylinder surface and the control input from actuators is the blowing and suction on the cylinder surface. Three different cost functionals to be minimized (J1 and J2) or maximized (J3) are investigated: J1 is proportional to the pressure drag of the cylinder, J2 is the square of the difference between the target pressure (inviscid flow pressure) and real flow pressure on the cylinder surface, and J3 is the square of the pressure gradient on the cylinder surface, respectively. Given the cost functionals, the flow variable to be measured by the sensors and the control input from the actuators are determined from the suboptimal feedback control procedure. Several cases for each cost functional have been numerically simulated at Re = 100 and 160 to investigate the performance of the control algorithm. For all actuations, vortex shedding becomes weak or disappears, and the mean drag and drag/lift fluctuations significantly decrease. For a given magnitude of the blowing/suction, reducing J2 provides the largest drag reduction among the three cost functionals.

Feedback Control of Linear Distributed Systems

1967 ◽  
Vol 89 (2) ◽  
pp. 379-383 ◽  
Author(s):  
Donald M. Wiberg
Keyword(s):  
Boundary Condition ◽  
Distributed Systems ◽  
Feedback Control ◽  
Closed Loop ◽  
The State ◽  
Loop System ◽  
Closed Loop System ◽  
Loop Equation ◽  
Control Feedback ◽  
And Control

The optimum feedback control of controllable linear distributed stationary systems is discussed. A linear closed-loop system is assured by restricting the criterion to be the integral of quadratics in the state and control. Feedback is obtained by expansion of the linear closed-loop equation in terms of uncoupled modes. By incorporating symbolic functions into the formulation, one can treat boundary condition control and point observable systems that are null-delta controllable.

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