document: Adjoint-based optimization of steady suction for disturbance control in incompressible flows The optimal distribution of steady suction needed to control the growth of single or multiple disturbances in quasi-three-dimensional incompressible boundary layers on a flat plate is investigated . The evolution of disturbances is analysed in the framework of the parabolized stability equations -LRB- PSE -RRB- . A gradient-based optimization procedure is used and the gradients are evaluated using the adjoint of the parabolized stability equations -LRB- APSE -RRB- and the adjoint of the boundary layer equations -LRB- ABLE -RRB- . The accuracy of the gradient is increased by introducing a stabilization procedure for the PSE . Results show that a suction peak appears in the upstream part of the suction region for optimal control of Tollmien-Schlichting -LRB- T-S -RRB- waves , steady streamwise streaks in a two-dimensional boundary layer and oblique waves in a quasi-three-dimensional boundary layer subject to an adverse pressure gradient . The mean flow modifications due to suction are shown to have a stabilizing effect similar to that of a favourable pressure gradient . It is also shown that the optimal suction distribution for the disturbance of interest reduces the growth rate of other perturbations . Results for control of a steady cross-flow mode in a three-dimensional boundary layer subject to a favourable pressure gradient show that not even large amounts of suction can completely stabilize the disturbance
doc_bio_tags: O O O B I O B I O B I O O O O B I O O O O O O O O O O O O O O O O O B I O O O O O O O O O O O O O O B I I O O O O O O O O O O O O O O O O O O O O B I I O O O O O O O O O O O O O O O O O O O O O O O O O B I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O B I I O O O O O O B I O O O O O O O O B I I O O B I O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O O
extractive_keyphrases: steady suction disturbance control incompressible flows flat plate parabolized stability equations stabilization procedure steady streamwise streaks oblique waves adverse pressure gradient mean flow
abstractive_keyphrases: adjoint-based optimization quasithree-dimensional incompressible boundary layers gradient-based optimization procedure tollmien-schlichting waves steady cross-flow mode laminar-turbulent transition