Long lasting modifications to vortex shedding using a short plasma excitation.

A unique phenomenon in flow control is described, where the lift and drag on a circular cylinder could be modified for over eight vortex shedding cycles by a short pulse of dielectric-barrier-discharge plasma. This is equivalent to flow control for over 150 times the pulse duration, which seems to be due to a secondary vortex initiated by plasma that interacts with the von Kármán vortex formation and temporarily amplifies or suppresses the vortex street. Depending on the pulse timing, the drag and lift fluctuations could be increased by 22% and 50% or reduced by 8% and 40%, respectively, with a power saving ratio over 1000.