Large-eddy breakup scheme for turbulent viscous drag reduction

A concept for reducing turbulent skin friction drag by altering/controling the large coherent eddy structures within the turbulent boundary layer is proposed. Results of an ongoing experimental and numerical investigation to develop large-eddy breakup devices (LEBU devices) are presented and indicate that the average skin friction drag downstream of the LEBU devices is reduced by up to 24% compared to "undisturbed" flat plate levels; device drag requires further reduction before net drag reductions can be realized. Future work is discussed and will focus on reducing device drag by taking advantage of the unsteady "freestream" ahead of the LEBU devices.