Adjoint-based Suction Optimization for 3D Boundary Layer Flows.

Authors: Pralits, J. O., Hanifi, A.
Document Type: Report
Pubstate: Published
Journal: FFA TN 2000-58
Year: 2000


The optimal distribution of suction to control disturbance growth is investigated for three-dimensional incompressible boundary layer flows on a flat plate. Optimal control theory is used and the problem is defined as input/output problem where the input is the wall-normal velocity component of the mean flow and the output is a measure of the disturbance kinetic energy. The optimization routine is gradient based and the gradients are derived using adjoint technique. Our investigation shows how the adjoint of the parabolized stability equations (APSE) and the adjoint of the boundary layer equations (ABLE) are coupled. Results show the optimal suction distribution to control steady streamwise streaks and oblique Tollmien-Schlichting waves in a three-dimensional boundary layer on a flat plate. A validation of the gradients is done where the gradients derived using the adjoint equations are compared with those obtained from a finite-difference calculation. An appendix exist with the complete derivation of the gradients and the adjoint equations.