Localized Finite-time Lyapunov Exponent for Unsteady Flow Analysis
2009 (English)Conference paper (Refereed)
The Finite-time Lyapunov Exponent (FTLE) is a measure for the rate of separation of particles in time-dependent flow fields. It provides a valuable tool for the analysis of unsteady flows. Commonly it is defined based on the flow map, analyzing the separation of trajectories of nearby particles over a finite-time span. This paper proposes a localized definition of the FTLE using the Jacobian matrix along a pathline as generator of the separation. The localized FTLE (L-FTLE) definition makes only use of flow properties along the pathline. A fast computation algorithm is presented that efficiently reuses FTLE values from previous time steps, following an idea similar to FastLIC. The properties of L-FTLE are analyzed with focus on the sensitivity to the parameters of the algorithm. It is further compared to the flow map based version under consideration of robustness to noise.
Place, publisher, year, edition, pages
2009. 265-274 p.
Fluid Mechanics and Acoustics
IdentifiersURN: urn:nbn:se:liu:diva-128047OAI: oai:DiVA.org:liu-128047DiVA: diva2:928765
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