Abstract
Mixing of two fluids under a very low Reynolds number condition such as a flow in a microfluidic device is governed by molecular diffusion. Therefore, mixing effectiveness can be evaluated by the size of the interfacial area between two fluids. Numerical simulations of an active chaotic micromixer have been performed and finite time lyapunov exponents have been calculated in order to estimate temporal and spatial expansion rates of the interfacial area. The spatial distributions of Lyapunov exponents are shown and the possibility of a micromixer design using lyapunov exponents are discussed.
