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

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.

Cluster-based network model

“…Promising strategies include riblets (Walsh & Lindemann 1984), compliant surfaces (Luhar, Sharma & McKeon 2016), spanwise wall oscillations (Jung, Mangiavacchi & Akhavan 1992; Quadrio, Ricco & Viotti 2009) and spanwise travelling waves with a Lorentz force (Du & Karniadakis 2000) or wall-normal deflection (Klumpp, Meinke & Schröder 2011; Albers et al. 2020). In this study, a spatio-temporal surface deformation with transverse travelling waves is chosen targeting aerodynamic applications.…”

“…In a numerical partner study, the actuation parameters were improved, yielding 31 % drag reduction (Albers et al. 2020; Fernex et al. 2020).…”

Cluster-based network modeling—From snapshots to complex dynamical systems

“…Many passive ( 38 , 39 ) and active ( 40 , 41 ) actuation techniques have been investigated to reduce the skin friction drag. In this study, skin friction reduction on a turbulent boundary layer is achieved by means of a spanwise traveling surface wave ( 31 , 42 ).…”

“…The superscript + denotes variables scaled with the friction velocity and the viscosity. Details about the computational setup can be found in the work of Albers et al ( 31 ). The actuation parameters are λ + = 1000, T + = 120, and A + = 60.…”

Formation Mechanism of an Adherent Vortex in the Side Pump Sump of a Pumping Station

“…Abreu et al [19] used direct numerical simulation to analyse turbulent channel flow and obtained its turbulent distribution law through the spectral inherent orthogonal decomposition method and a solvent. With regard to research on the flow around problem, Albers et al [20] used the LES model and analysed the flow around the wall of a straight plate and the influence of the transverse surface wave of wingspan propagation in the turbulent boundary layer under zero pressure gradient. Many scholars have combined two methods to verify each of them [21], and some of them introduce machine learning method [22], but only a few used a method that combines physical model testing and theoretical analysis [23].…”