ABSTRACT
This chapter aims to provide an introductory review on characterization of chaotic stirrers using appropriate numerical tools. Various active micromixers using two-dimensional time-dependent flow to achieve chaotic advection have been developed. To achieve chaotic advection in three-dimensional steady flow in a geometry that has certain complexity created by three-dimensionality, microconduits can be used. In three-dimensionality, chaotic advection can be achieved by using passive micromixer designs, which can efficiently operate at limited kinematic conditions because of the availability of beneficial flow mechanisms, such as the Dean vortices, the expansion vortices, or the secondary flows. Mathematical modeling and numerical simulations of mixing in lab-on-a-chip devices provide a convenient and fast method for optimizing the design and operation parameters of a chaotic stirrer, which otherwise would require enormous effort. To quantitatively characterize the chaotic strength in the case of featureless Poincare sections, the Lyapunov exponent needs to be calculated.
