I am working on the Mixing in microchannels. I am performing 3D numerical simulations in order to understand and optimize the mixing at the microscale in an active micromixer. I am using the CFD software Fluent for the computation and Gambit to create the geometry. The micromixer I am working on is composed of one main channel, where the fluids to be mixed are injected, and of three pairs of side channels. The mixing is achieved in the laminar flow by perturbing the main flow with transverse oscillating flows imparted in the secondary side channels. This stretches and folds the layers in the flow stream causing chaotic advection, thereby increasing mixing. The main channel is 200 microns wide, 100 microns deep and 1350 microns long. Simulations were performed with either the first or all three side channels activated. The mixing is quantified using the Mixing Variance Coefficient function. We achieve a good mixing of the two fluids whith the three side channels activated within 0.1 second. Dr. Frederic BOTTAUSCI is in charge of the experimental study of the mixing.