TY - GEN A1 - Kuhn, Alexander A1 - Engelke, Wito A1 - Rössl, Christian A1 - Hadwiger, Markus A1 - Theisel, Holger T1 - Time Line Cell Tracking for the Approximation of Lagrangian Coherent Structures with Subgrid Accuracy N2 - Lagrangian Coherent Structures (LCS) have become a widespread and powerful method to describe dynamic motion patterns in time-dependent flow fields. The standard way to extract LCS is to compute height ridges in the Finite Time Lyapunov Exponent (FTLE) field. In this work, we present an alternative method to approximate Lagrangian features for 2D unsteady flow fields that achieves subgrid accuracy without additional particle sampling. We obtain this by a geometric reconstruction of the flow map using additional material constraints for the available samples. In comparison to the standard method, this allows for a more accurate global approximation of LCS on sparse grids and for long integration intervals. The proposed algorithm works directly on a set of given particle trajectories and without additional flow map derivatives. We demonstrate its application for a set of computational fluid dynamic examples, as well as trajectories acquired by Lagrangian methods, and discuss its benefits and limitations. T3 - ZIB-Report - 13-71 KW - time-dependent vector fields KW - flow field visualization KW - Lagrangian Coherent Structures (LCS) KW - finite-time Lyapunov exponents (FTLE) KW - time lines Y1 - 2013 UR - https://opus4.kobv.de/opus4-zib/frontdoor/index/index/docId/4305 UR - https://nbn-resolving.org/urn:nbn:de:0297-zib-43050 SN - 1438-0064 ER -