Actuation response model from sparse data for wall turbulence drag reduction

Abstract

Drag reduction of an actuated turbulent boundary layer at a momentum-thickness-based Reynolds number Re${}_{\ensuremath{\theta}}$ = 1000 is computed, modeled, and predicted. The drag reduction for the set of actuation parameters is modeled using 71 large-eddy simulations. This drag model allows extrapolation outside the actuation domain for larger wavelengths and amplitudes. The modeling novelty combines support vector regression for interpolation, a parametrized ridgeline leading out of the data domain, a scaling for the drag reduction, and a discovered self-similar structure of the actuation effect.