Dresden 2009 – wissenschaftliches Programm

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DY: Fachverband Dynamik und Statistische Physik

DY 16: Fluid dynamics I

DY 16.9: Vortrag

Mittwoch, 25. März 2009, 17:00–17:15, ZEU 255

Quantification of mixing in micro-channels using finite time Lyapunov exponents — Aniruddha Sarkar and •Jens Harting — Institute for Computational Physics, University of Stuttgart, Germany.

The staggered herring-bone mixer (SHM) is a chaotic micromixer, which was recently developed by A.Stroock et al.. We obtain mixing here by a process called "chaotic advection", which occurs due to repeated stretching and folding of the fluid interfaces, even at low Reynold’s number.

The ability of the fluids to mix well depends on the rate at which chaotic advection occurs in the mixer. In order to calculate the chaotic strength of a micromixer, we analyse finite-time Lyapunov exponents(FTLE). We simulate the fluid flow using the lattice Boltzmann method(LBM), introduce massless and non interacting tracer particles and from their trajectories we calculate the Lyapunov exponents. We calculate the Lyapunov exponents and then use this method to optimize the performance of the SHM. We varried the geometrical structures of the SHM and reproduce the optimal parameters known from the literature. Further we show that the mixing properties can be increased by adding hydrophobic surfaces.