Statistics of a turbulent boundary layer with sequential favorable and adverse pressure gradients

A turbulent boundary layer is studied under an imposed favorable and adverse pressure gradient in sequence. A deformable ceiling panel (Parthasarathy & Saxton-Fox, 2022) is used to impose multiple pressure gradients on the boundary layer. This talk will focus on the turbulent statistics and structures in the non-equilibrium statically held pressure gradients. Planar particle image velocimetry and preliminary stereo particle image velocimetry data will be discussed. In previous studies (Parthasarathy & Saxton-Fox, 2023), the formation of an internal boundary layer has been observed under various pressure gradients of this type (FAPGs), however, the process of formation of the internal layer has not been studied. This talk focuses on observing the statistics in the region where the internal layer is formed as well as the preceding FPG region. This talk will also look at the statistics in the spanwise-wall normal plane at the point of neutral pressure gradient between the FPG and the APG. Experiments are being performed at multiple Re_Tau, in order to investigate any Reynolds number dependence, however, this talk will only focus on Re_Tau=1000.