Control and system identification of a separated flow

A procedure to construct linear optimal control for separated flows is presented. Unlike previous works in which a system model is derived from the linearized Navier-Stokes equations, we use an approximate linear model for the flow system generated by a system identification method based on input-output data sequences from numerical solutions of the Navier-Stokes equations. The approximate model is used in linear quadratic Gaussian synthesis to compute feedback control laws. Various properties of the identified model are tested and discussed. The closed-loop control is applied to a two-dimensional separated boundary layer, aiming at reducing its separation bubble size. (C) 2008 American Institute of Physics. [DOI: 10.1063/1.3005860]