A comparison of methods for fast computation of time-varying FTLE fields
S. L. Brunton and C. W. Rowley
Chaos (submitted), September 2009.
Abstract:
This paper presents an efficient method for computing finite time Lyapunov exponent (FTLE) fields in unsteady flows by approximating the particle flow map and eliminating redundant particle integrations in neighboring flow maps. Two classes of flow map approximations based on composition of intermediate flow maps are investigated; in the first, a time-T map is constructed by composing a number of time-dt maps (unidirectional), and the second class constructs a flow map by composing both forward and backward time intermediate maps (bidirectional). All methods are evaluated against the exact FTLE field calculation using analytic estimates as well as computational benchmarks on the criteria of accumulated error and total computational time.
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