Particle tracking velocimetry and accelerometry (PTVA) measurements applied to quasi-two-dimensional multi-scale flows

We have developed and validated a new adaptive method, particle tracking velocimetry and accelerometry (PTVA), to measure velocity and acceleration from the post-processing of particle tracking ( PT) data. This method is shown to be more accurate than non-adaptive methods based on PT: errors are about six times smaller on velocity measurements and about four times smaller on acceleration ones. We apply this method to a turbulent-like flow generated and controlled in the laboratory. Taking advantage of the Eulerian repeatability of our multi-scale laminar flow, we are able to extract the acceleration field, a, and all terms of Navier-Stokes equation. To complete this we extract u.a and del.a fields. We finally compare the probability density function of the acceleration components of our turbulent-like flow with one of the highly turbulent flows and show that they are similar. The quality of these PTVA results and their robustness (in particular to local convection) are extremely encouraging. This method allows access to a deeper insight into the physic of turbulent-like flows and its high accuracy may apply to a broader range of flows