Advection-based temporal reconstruction technique for undersampled PIV data

The present work investigates the use of an advection-based supersampling technique to increase the temporal resolution of PIV datasets. The approach utilizes the available spatial information to determine the velocity of a fluid particle at some intermediate time. A Taylor series expansion is used to obtain the instantaneous fluid trajectory from past and future time instants. The velocity field is then estimated using a temporally based weighted average of the forwards and backwards predictions. The performance of the technique is directly compared with a bilinear interpolation approach for two synthetic PIV datasets: the 1-DOF vortex induced vibrations (VIV) of a circular cylinder within the laminar vortex shedding regime (Re=150), and a turbulent round jet (Re=10,000). A proper orthogonal decomposition (POD) is used to identify coherent wake structures and compare their energy distribution before and after application of the super-sampling method. The technique demonstrates the ability to reconstruct key wake dynamics for both datasets, indicating that the required acquisition rate requirements of PIV measurements can be reduced through consideration of the available spatio-temporal information.