Identification of true particle image displacement based on false correlation symmetry at poor signal peak detectability

Abstract

A novel extension of cross-correlation particle image velocimetry (PIV), based on false correlation symmetry (FCS) around the real signal peak, is proposed to detect the true displacement correlation below noise level at poor signal conditions. The technique is introduced in the light of the main influential parameters, namely particle image loss, velocity gradients, correlation overlapping, and non-uniform illumination. Searching for FCS in the Fourier domain and among correlation peaks is examined. The latter is evaluated by Monte-Carlo simulation on synthetic PIV images and also on a real vortex shedding flow field. Lower than one detectability (D0 < 1) and the possibility to achieve higher spatial resolution are the clear merits of using FCS.