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Integrated Computation of Finite Time Lyapunov Exponent During ...

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Introduction<br />

<strong>Finite</strong> <strong>Time</strong> <strong>Lyapunov</strong> <strong>Exponent</strong> (FTLE)<br />

Avg. stretching rate <strong>of</strong> initially adjacent tracers over finite time.<br />

Ridges show strong correspondence with Lagrangian coherent<br />

structures (LCS): Invariant transport barriers, skeleton <strong>of</strong> tracer<br />

patterns. [Haller, 2001, Shadden et al., 2005]<br />

Relatively modern FTLE/LCS theory contributed new understanding to<br />

many fields<br />

Typically computed via algorithmically simple, computationally<br />

expensive post-processing <strong>of</strong> experimental/numerical data<br />

Enormous number <strong>of</strong> particle advections<br />

Careful memory management.<br />

Fewer velocity fields ⇒ more uncertainty.<br />

Speedup possible: AMR [Miron et al., 2012], Ridge<br />

tracking [Lipinski and Mohseni, 2010], GPU<br />

acceleration [Conti et al., 2012],<br />

Repelling<br />

trajectories [Shadden et al., 2005]<br />

Atmospheric events [Lekien and Ross, 2010] Granular flow in a tumbler [Christov et al., 2011]<br />

Startup <strong>of</strong> a swimming<br />

fish [Conti et al., 2012]<br />

Finn & Apte FTLE & DNS Integration 2

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