Volumetric measurements of an adverse-pressure-gradient turbulent boundary layer using single-camera light-field PIV

As a novel volumetric particle image velocimetry technique, Single-Camera Light-Field PIV (LF-PIV) is able to reconstruct three-dimensional flow fields using a single camera. The merits of LF-PIV lie in its concise hardware setup and minimum optical access requirement. Its capability has been proved in many experimental investigations. In this study, LF-PIV is used to measure a self-similar Adverse Pressure Gradient Turbulent Boundary Layer (APG-TBL). Experiments are performed in a large water tunnel at the Laboratory for Turbulence Research in Aerospace and Combustion (LTRAC), Monash University. Twenty independent batches of light-field PIV images are captured for both inner and outer flow, each consisting of 250 instantaneous image pairs. Instantaneous 3D velocity fields are reconstructed with the GPU accelerated DRT-MART and 3D cross-correlation methods and compared with two-dimensional PIV (2D-PIV) results. Preliminary results show that though limited by the experiment conditions and PIV algorithms developed in 2016, similar accuracies to 2D-PIV are achieved near and above the boundary layer. With the volumetric calibration method that compensates optical distortions caused by lens defect and misalignment between the Microlens Array (MLA) and image sensor, the resolution of LF-PIV is greatly improved.