Control of streamwise vortices using selective suction

The breakdown of streamwise vortices was controlled using selective suction. A Gortler flowfield was used to produce streamwise vortices emulating turbulent boundary-layer eddies in a steady laminar-like environment. Suction was applied at single locations under the low-speed region between counter-rotating vortex pairs. A suction coefficient two orders of magnitude less than that required for an asymptotic profile was sufficient to significantly delay the breakdown of the vortices. At high-suction rate, however, premature breakdown resulted due to the creation of an additional instability in the spanwise direction. Results suggest that an ideal control method should produce fuller profiles in the normal direction and eliminate the difference between low- and high-speed regions in the spanwise direction.