Three-dimensional flow field reconstruction in the wake of a confined square cylinder using planar PIV data

Abstract

A method is presented to perform the three-dimensional reconstruction of the velocity field in laminar flows using planar PIV data. The developed method relies on a convenient, repeated application of two data processing tools developed by two of the authors and called the higher order dynamic mode decomposition and the spatio-temporal Koopman decomposition. The present reconstruction method is an extension of a general method recently presented by three of the authors (Pérez et al., 2020), in which synthetic PIV data (obtained via numerical simulation) along three mutually orthogonal families of planes were used. In this article, instead, actual experimental data are considered, which requires additional data processing tools, developed in the article, to both cope with experimental noise and synchronize the various PIV datasets obtained in different timespans. The method is applied to analyze the wake of a square cylinder confined in a channel, at moderate Reynolds number. Due to limitations of the experimental setup used to obtain data for this configuration, only two families of planar PIV measurements are available that are contained in planes parallel to the sides of the channel. Because of this limitation, only the streamwise velocity component is three-dimensionally reconstructed. The performance of the method is tested in the wake of the confined square cylinder, comparing the reconstructed data with experimental PIV data measured on additional test planes (not used in the reconstruction). The obtained reconstructions of the streamwise velocity are reasonably accurate.