Lagrangian coherent track initialization

Advances in time-resolved three-dimensional Particle Tracking Velocimetry (4D-PTV) techniques have consistently revealed more accurate Lagrangian particle motions. A novel track initialization technique as a complementary part of 4D-PTV, based on local temporal and spatial coherency neighbor trajectories, is proposed. The proposed Coherent Track Initialization (LCTI) applies physics-based Finite Time Lyapunov Exponent (FTLE) to build four frame coherent tracks. We locally determine structures among trajectories by using the FTLE boundaries (i.e., ridges) distinguish clusters To evaluate technique, we created an open-access synthetic Eulerian dataset wake downstream smooth cylinder at Reynolds number equal 3900 obtained from direct numerical simulation. Performance method three characteristic parameters, scale, concentration density), noise ratio, showed robust behavior finding true tracks compared recent algorithms. Sensitivity LCTI untracked wrong also discussed. address capability function 4D-PTV scheme tracking challenge. that prevents divergence flows with high concentrations. Finally, was demonstrated jet impingement experiment. found be reliable tool complex flow motions, strength for velocity acceleration gradients.