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DY: Fachverband Dynamik und Statistische Physik
DY 12: Poster I
DY 12.11: Poster
Tuesday, March 24, 2009, 14:30–16:30, P1A
Invariants of the velocity gradient tensor in turbulent flows — •Anton Daitche, Michael Wilczek, and Rudolf Friedrich — Institut für Theoretische Physik, Wilhelm-Klemm-Str. 9, 48149 Münster
The velocity gradient tensor Aij=∂jui can be used to characterize the fine scale motion of a turbulent flow. For example the local topology of the velocity field is determined by the rate of strain tensor and the rate of rotation tensor, which are the symmetric and asymmetric parts of Aij. We study Aij along Lagrangian trajectories in homogeneous, isotropic and stationary turbulence. Due to the isotropy the pdf of Aij is a function of the invariants of this tensor. A detailed analysis of the statistics of these invariants will be presented. Furthermore we estimate the drift of these invariants and evaluate the statistical properties of its fluctuations.