Stretching and folding in finite time
Abstract
Complex flows mix efficiently, and this process can be understood by considering the stretching and folding of material volumes. Although many metrics have been devised to characterize stretching, fewer are able to capture folding in a quantitative way in spatiotemporally variable flows. Here, we extend our previous methods based on the finite-time curving of fluid-element trajectories to nonzero scales and show that this finite-scale finite-time curvature contains information about both stretching and folding. We compare this metric to the more commonly used finite-time Lyapunov exponent and illustrate our methods using experimental flow-field data from a quasi-two-dimensional laboratory flow. Our new analysis tools add to the growing set of Lagrangian methods for characterizing mixing in complex, aperiodic fluid flows.
Document Details
- Document Type
- Pub Defense Publication
- Publication Date
- Feb 01, 2016
- Source ID
- 10.1063/1.4941256
Entities
People
- Erik M. Bollt
- Nicholas T. Ouellette
- Tian Ma
Organizations
- Army Research Office
- Clarkson University
- National Geospatial-Intelligence Agency
- National Science Foundation
- Office of Naval Research
- Stanford University
- Yale University