Sixth International Symposium on Turbulence and Shear Flow Phenomena
DOI: 10.1615/TSFP6
DNS OF OSCILLATING RIBLETS FOR TURBULENT DRAG REDUCTION
pages 587-591
DOI: 10.1615/TSFP6.940
ABSTRACT
Blade-shaped riblets are tilted sinusoidally at specific frequencies to reduce turbulent friction drag. Within this investigation, the overall drag reduction of stationary riblets could be improved by the oscillation from 8.6% to 11.1%. Two examplary cases are presented, one showing an increase in drag reduction and one with only minor changes compared to stationary riblets. Detailed analysis of data from direct numerical simulations reveals that the additional drag reduction is mostly related to a smaller contribution from the riblet tips which is caused by a secondary motion of low-speed fluid. The effect is accompanied by a reduction of turbulent activity within the main flow.