Estimation of 3D ship airwakes using dual-plane PIV

A high-speed, dual-plane, stereoscopic particle image velocimetry technique was complemented by a flow estimation method to construct three-dimensional Simple Frigate Ship 2 airwakes. In particular, three pairs of mutually-orthogonal streamwise and spanwise planes were measured, with the ultimate goal of simultaneously estimating various spanwise planes using an invariant streamwise plane. First, the dual-plane measurements were divided into training and test sets. Then, for each pair of planes in the training set, the large-scale structures spanning both (streamwise and spanwise) planes were learned using the proper orthogonal decomposition (POD) spatial modes. Next, in the test set, only the streamwise plane was assumed to be known, and the POD temporal modes (corresponding to the learned spatial modes) were estimated to construct low-order models of each spanwise plane. This approach found excellent agreement between the measured and estimated low-order spanwise planes, as evaluated by three metrics. Ultimately, the velocities across three spanwise planes were simultaneously calculated, demonstrating the experimental framework’s ability to perform time-dependent, three-dimensional, low-order reconstruction of complex turbulent flows.