S. L. Brunton and C. W. Rowley, Fast computation of finite-time Lyapunov exponent fields for unsteady flows. Chaos 20 : 017503, March 2010. http://carlsbad.princeton.edu/~steve/papers/BrRo_Chaos20.pdf ABSTRACT: ```
This paper presents new efficient methods for computing finite-time
Lyapunov exponen FTLE fields in unsteady flows. The methods approximate
the particle flow map, eliminating redundant particle integrations in
neighboring flow map calculations. Two classes of flow map
approximations are investigated based on composition of intermediate
flow maps: unidirectional approximation constructs a time-T map by
composing a number of smaller time-h maps, while bidirectional
approximation constructs a flow map by composing both positive- and
negative-time maps. The unidirectional method is shown to be fast and
accurate, although it is memory intensive. The bidirectional method is
also fast and uses significantly less memory; however, it is prone to
error which is large in regions where the opposite-time FTLE field is
large, rendering it unusable. The algorithms are implemented and
compared on three example fluid flows: a double gyre, a low Reynolds
number pitching flat plate, and an unsteady ABC flow.
``` |

ResearchBlog >