Some Aspects of Strain Vorticity and Material Element Dynamics as Measured with 3D Particle Tracking Velocimetry in a Turbulent Flow

Lüthi B.

The motivation for this thesis is to make use of the essentially Lagrangian method of three dimensional Particle Tracking Velocimetry (3D-PTV) to eludicate some mechanisms of turbulence that previous Eulerian approaches could not access. In particular, this means to further develop the non intrusive flow measurement technique of 3D-PTV such, that the full tensor of velocity derivatives can be measured along trajectories of fluid particles. This Lagrangian approach should give new insight into some aspects of strain and enstrophy dynamics. Moreover it will add to the understanding of the behavior of material volumes and surfaces and the differences between stretching of vortex lines and material lines.