Recent developments of dense Lagrangian Particle Tracking applied to the characterization of turbulent flows - Shake-The-Box and FlowFit

Abstract

Shake-The-Box (STB) is a novel time-resolved 30 Lagrangian particle tracking method for densely seeded flows developed at OLR and is of particular use for turblence research. STB overcomes the ill-posed reconstruction problem for 30 particle distributions at high seeding densities present for each single time­step (as known for tomo-PIV and PTV) by pre-solving the problem for each predicted time-step in a cascade of reduced complexity along a time series of images. As a result STB delivers accurate and dense 30 Lagrangian track data in large volumes. The velocity and acceleration information at the track positions can be used for a Navier-Stokes-regularized interpolation method (FlowFit) resulting in high resolution time-resolved 30 velocity gradient tensor information on a regular grid enabling combined Eulerian and Lagrangian investigations. Furthermore the time-resolved 30 pressure field can be directly computed with the FlowFit scheme.