Experimental investigation of scale decomposition in a self-similar adverse pressure gradient turbulent boundary layer flow near separation using proper orthogonal decomposition

This thesis is an investigation of a decelerating turbulent boundary layer (TBL) near separation using particle image velocimetry. Momentum and scale decompositions are performed using proper orthogonal decomposition to investigate high- and low-momentum intense large-scale motions, as well as large- and small-scale motions. Below the displacement thickness height, high-momentum motions have larger contributions to the Reynolds stresses. Above it, the opposite is the case. The contributions of the large scales to the Reynolds stresses in the outer region are up to 80%. Near the wall, most contributions come from the small scales. These results indicate that the mean skin friction is mostly due to the small scales at the wall and partly due to the large-scale structures.