Investigation of turbulent/non-turbulent interfaces in high Reynolds number adverse pressure gradient boundary layers

Abstract

This study utilises high-magnification two-dimensional Particle Image Velocimetry (2D-PIV) to investigate adverse pressure gradient (APG) turbulent boundary layers at high friction Reynolds numbers, which evolve from a canonical zero pressure gradient (ZPG) upstream condition. The primary focus is on comparing the turbulent/non-turbulent interface (TNTI) for ZPG and APG at high Reynolds number. Local kinetic energy (LKE) and spanwise vorticity methods are considered for TNTI detection, with Joint Probability Density Functions (JPDFs) for LKE/vorticity and wall-normal distance used to determine the respective thresholds and estimate corresponding TNTI heights. A sensitivity analysis of the me..