Optimization of a 4D-PTV metrology for the characterization of a turbulent flow at very small scales.
Résumé:
The fundamental study of turbulence is of significant importance due to its dominant role in many fields of physics, engineering sciences, astrophysics, aeronautics, etc. Turbulent dissipation plays a central role in turbulent flow and is therefore an important quantity in turbulence models. With the aim of characterizing this dissipation, the present work is based on a particle tracking technique called “Shake-The Box” to measure three-dimensional velocity fields as function of time at a resolution which can approach dissipative scale. The experimental setup and processing of the Shake the Box technique have been optimized and pushed to their limits in order to improve the spatial resolution and the accuracy of the measured Lagrangian trajectories. The approach used in this thesis was based not only on experimental data but also on synthetic PIV images based on direct numerical simulation of the Navier Stokes equations. The quantitative and qualitative investigation allows us to define the optimal parameters for our targeted application on a Giant Von Karman flow and gives the limits of the method.
