Numerical Study of the Accuracy of the Particle Image Velocimetry Technique in High-Speed Turbulent Flows

In this study, we investigate the accuracy of the Particle Image Velocimetry (PIV) technique for the characterization of high-speed turbulence, which is representative of the flows typically found in modern practical and experimental combustion systems. We carry out direct numerical simulations and subsequently perform synthetic PIV reconstruction of the resulting three-dimensional turbulent flow field at Reynolds numbers $\approx 5000$ and Karlovitz numbers $\approx 200$ (premixed CH$_4$-air under atmospheric conditions). The flow field is uniformly seeded with 0.3 $\mathrm{\mu}$m monodispersed Al$_2$O$_3$ particles that represent typical PIV particles used in experiments, along with initially co-located massless Lagrangian tracer particles to recover the actual flow pathlines. We address the following questions: 1) How do PIV particles affect the carrier flow field? 2) How well do PIV particles sample the flow field of interest? 3) How closely do PIV particles follow the flow pathlines? 4) What is the accuracy of the PIV reconstructed flow field when compared to the true flow field? Finally, we conclude by discussing the implications of using PIV as a diagnostic tool for high-speed reacting and non-reacting flows.