Drag Reduction and Energy Saving by Spanwise Traveling Transversal Surface Waves for Flat Plate Flow

2019/08/26 by Marian Albers, Pascal S. Meysonnat, Albers, Marian +9
Physics and Astronomy · #FOS: Physical sciences #Fluid Dynamics (physics.flu-dyn) #physics.flu-dyn

paper · pdf · doi:10.48550/arxiv.1908.09565

arxiv created 2019/08/26 · arxiv updated 2019/08/27

Abstract

Wall-resolved large-eddy simulations are performed to study the impact of spanwise traveling transversal surface waves in zero-pressure gradient turbulent boundary layer flow. Eighty variations of wavelength, period, and amplitude of the space- and time-dependent sinusoidal wall motion are considered for a boundary layer at a momentum thickness based Reynolds number of Re_θ= 1000. The results show a strong decrease of friction drag of up to 26 % and considerable net power saving of up to 10 %. However, the highest net power saving does not occur at the maximum drag reduction. The drag reduction is modeled as a function of the actuation parameters by support vector regression using the LES data. A substantial attenuation of the near-wall turbulence intensity and especially a weakening of the near-wall velocity streaks are observed. Similarities between the current actuation technique and the method of a spanwise oscillating wall without any normal surface deflection are reported. In particular, the generation of a directional spanwise oscillating Stokes layer is found to be related to skin-friction reduction.

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