Structure of high reynolds number adverse pressure gradient turbulent boundary layer

A high Reynolds number adverse pressure gradient turbulent boundary layer experiment was carried out in the large wind tunnel of Laboratoire de Mécanique de Lille using synchronized stereo PIV systems and a hot-wire rake of 143 single wire probes. A 2D bump was used to create converging-diverging flow inside the test section. Measurement were performed on the decelerating part of the bump. Reynolds number based on the momentum thickness was 17 100. In order to investigate structural characteristics of the high Reynolds number turbulent boundary layer under influence of strong adverse pressure gradient in a statistical sense, simultaneously sampled hot-wire data of 143 probes were used to compute two-point correlations on both streamwise-spanwise (XZ) planes parallel to wall and streamwise-wall-normal (XY) planes normal to thewall. The results presented in this paper indicate that most of the activity creating significant correlations is confined from wall to top of the log-layer, which is about y⁺ of 700 in this case. Maximum streamwise extent of the correlation on XZ plane is approximately ±4.5δ. Similarly, the elongated correlations in the streamwise direction on XY planes reach maximum 10d in length inside the log-layer. The wake region produces weak correlations compared to the onesobserved inside the log-layer.