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.