3D PTV and its application on Lagrangian motion

Three-dimensional particle tracking velocimetry (3D PTV) is a flow measurement technique for the determination of velocity vectors and trajectories within a three-dimensional observation volume. This makes this technique suitable not only for Eulerian but also for Lagrangian investigation of flow phenomena, especially in the field of turbulence and turbulent diffusion.

The principle and the application on open channel flow of 3D PTV are briefly described in the first part of this paper. By decomposition of the velocity vectors velocity profiles and turbulence intensities are derived and presented in the second part. Turbulent energy dissipation, Kolmogorov length and time scales and Taylor micro scales are computed from the measured data sets. In the Lagrangian analysis pdf's of the Lagrangian acceleration, correlation coefficients and Taylor micro scales are determined. The individual determination of the particle positions and displacements allows finally the application on the one and two particle approaches for turbulent diffusion from Taylor (1921), Richardson (1926) and Batchelor (1949, 1952).