Flow stabilisation by Dirichlet boundary control

Re–attachment of separated flow is investigated for the model problem of a backward facing step at moderate Reynolds number (up to 400), where the length of the detachment zone is reduced by blowing in (or sucking out) fluid through a nozzle below the step. Both optimal feed forward control as well as a simple feedback control are considered, with surprisingly good results obtained by a very simple (non–optimal) linear feedback controller. Numerical results are shown. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)