26 Apr Improving the Reliability of PIV Uncertainty Methods
PIV uncertainty quantification is important for comparison with CFD simulations and engineering design, but is challenging due to the complex non-linear measurement chain which involves a large number of parameters. Multiple assessments show that none of the current methods can reliably predict the actual uncertainty across a range of experiments and estimates can vary, and it is difficult for a user to choose a particular method for an experiment where the error distribution is unknown.
We propose a method to estimate the reliability of a PIV uncertainty method from its sensitivity to particle image perturbations. The method is local, instantaneous and automated, and estimates the sensitivity of the uncertainty estimates by random addition of unpaired particles to the interrogation window and measuring the response of the uncertainty method. The reliability metric is termed the Meta-Uncertainty and represents the rate of change of the inter-quartile range of uncertainty perturbations arising from increasing levels of controlled particle addition.
We also apply the meta-uncertainty as a weighting metric to combine uncertainty estimates from individual schemes, and show performance improvements in planar and stereo PIV measurements across a range of canonical flows.