Lagrangian particles in turbulence: An experimental data set

This data set contains the coordinates of Lagrangian trajectories in a quasi-homogeneous isotropic turbulent flow. The trajectories were measured in a water tank experiment using the 3D-PTV method through the MyPTV open-source software (https://github.com/ronshnapp/MyPTV). The total duration of this data set corresponds to 20 seconds of recording at a rate of 500 Hz, and it holds roughly 575,000 trajectories. The data is stored in two text files in a tab-separated format, where each file coresponds to 10 seconds of recording. Each row in the files outlines a single measurement point from the experiment. The various columns correspond to the following information: 1 - trajectory_id 2 - x [mm] 3 - y [mm] 4 - z [mm] 5 - vx [mm/frame] 6 - vy [mm/frame] 7 - vz [mm/frame] 8 - ax [mm/frame^2] 9 - ay [mm/frame^2] 10 - az [mm/frame^2] 11 - time [frame] where trajectory_id uniquely marks samples that correspond to the same physical trajectory; x, y, and z are the position components in the three orthogonal space directions; vx, vy, and vz correspond to the velocity components; ax, ay, and az that correspond to the acceleration components. The flow in the experiment was forced using a system of 8 propellers, powered by DC motors that were positioned at the corners of the cylindrical, octagonally shaped, water tank. The propellers were changing their direction of rotation at random time intervals with an average interval duration of 0.1 seconds. The root mean square of the turbulent flow fluctuations is about 100 millimeters per second. There is a time-averaged secondary circulation with a magnitude of roughly 66% of the root mean squared fluctuation strength. The Taylor microscale Reynolds number is estimated as about 188.