title: Predicting the enhancement of mixing-driven reactions in nonuniform flows using measures of flow topology.
abstract: The ability for reactive constituents to mix is often the key limiting factor for the completion of reactions across a huge range of scales in a variety of media. In flowing systems, deformation and shear enhance mixing by bringing constituents into closer proximity, thus increasing reaction potential. Accurately quantifying this enhanced mixing is key to predicting reactions and typically is done by observing or simulating scalar transport. To eliminate this computationally expensive step, we use a Lagrangian stochastic framework to derive the enhancement to reaction potential by calculating the collocation probability of particle pairs in a heterogeneous flow field accounting for deformations. We relate the enhanced reaction potential to three well known flow topology metrics and demonstrate that it is best correlated to (and asymptotically linear with) one: the largest eigenvalue of the (right) Cauchy-Green tensor.
authors.affiliation: Department of Civil and Environmental Engineering, Washington State University, Pullman, Washington 99164, USA.
authors.forename: Nicholas B
authors.initials: NB
authors.lastname: Engdahl
authors.affiliation: Hydrologic Science and Engineering, Colorado School of Mines, Golden, Colorado 80401, USA.
authors.forename: David A
authors.initials: DA
authors.lastname: Benson
authors.affiliation: Department of Civil and Environmental Engineering and Earth Sciences, University of Notre Dame, Notre Dame, Indiana 46556, USA.
authors.forename: Diogo
authors.initials: D
authors.lastname: Bolster