REYNOLDS-NUMBER EFFECTS ON LAMINAR MIXING IN THE KENICS STATIC MIXER

The Kenics static mixer was investigated numerically using Lagrangian methods to characterize mixer performance in laminar flow. Techniques from dynamical systems analysis (Poincare sections, tracking of fluid tracers, and the development of stretching histories for tracer elemen ts) as well as a more traditional mixing measure (the variation coeffi cient) were used to compare mixing performance at various Reynolds num bers. For creeping flow conditions (Re less than or equal to 10), the Kenics flow is globally chaotic and mixing performance is independent of Re. For Re = 100, significant islands of regular motion develop. Th ese islands do not exchange material with the remainder of the flow an d act as a barrier to uniform mixing. For Re = 1000, the Row is predom inantly chaotic again, but small islands remain, leading to less effec tive mixing than under creeping flow conditions. (C) 1998 Elsevier Sci ence S.A. All rights reserved.