Abstract: Spanwise oscillation has been studied extensively as an effective drag reducing tool. However, research on its impact on the shock wave/boundary layer interaction is still rare. In this paper, we perform a Direct Numerical Simulation (DNS) of oblique shock wave/boundary layer interaction at Ma=2.9 with 12° incident angle. Through a quantitative comparison with the case without oscillation, the impact of the oscillation on complex structures in size of separation bubbles, fluctuations of wall pressure and statistical characteristics of wall shear stresses is revealed. With strong spanwise oscillation, the separation position moves upstream and the intermittency length increases. The penetrating depth of the spanwise oscillation is about 4% of the separation bubble height due to the viscous dissipation of the boundary layer. Therefore, the general structures of the interaction will not be affected. Since the spanwise velocity is much larger than the streamwise velocity in the near wall region, the peak of probability density functions of the angle between wall shear stress components shifts from 0° to 80°-90°. The proper orthogonal decompositions of wall pressure and wall shear stresses indicate that the model energy will be transferred from the lower-order modes to higher-order ones, and the proportion of energy in low-frequency motion is reduced, while the structures after reattachment such as Görtler vortices will be strengthened.

Key words: shock wave/turbulent boundary layer interaction, spanwise oscillation, wall pressure fluctuations, proper orthogonal decomposition, probability density functions