An interconnected systems approach to flow transition control

Abstract

This paper presents the application of an interconnected systems approach to the flow transition control problem. The control system consists of a network of local controllers with dedicated actuators and sensors. The measured feedback signals used by the controllers are the local changes in wall shear force, and the generated control action is a local change in fluid wall normal velocities. The approach presented here does not require periodicity of the channel as was required by most earlier approaches. Thus, in contrast to previously proposed control schemes which operate in Fourier domain, this approach works in physical domain. Secondly it does not restrict the number of interacting units, thus allowing the application of MEMS arrays. In order to synthesize such controllers, first the dynamics of the fluid is converted into interconnected system form. The model is validated using a non-linear simulation environment developed in FLUENT, and by analysing the growth in the transient energy. The model is then used to synthesize an interconnected controller. The simulated closed-loop response shows that the controller can delay the transition by reducing the transient energy.