When a stream of a fluid past a bluff object, above a certain fluid velocity, vortices, which are shed from the object, can be observed downstream and make the wake oscillatory and unsteady.
Published in Chapter:
2D Numerical Study of a Micromixer Based on Blowing and Vortex Shedding Mechanisms
Maria Sanchez-Claros (Universidad de Málaga, Spain), Joaquin Ortega-Casanova (Universidad de Málaga, Spain), and Francisco Jose Galindo-Rosales (Universidade do Porto, Portugal)
Copyright: © 2019
|Pages: 35
DOI: 10.4018/978-1-5225-7138-4.ch003
Abstract
In this chapter, a numerical study and assessment of the mixing efficiency of a novel microfluidic device for mixing two fluids are presented. The device under study consists of a two-dimensional straight microchannel with a square pillar centered across the channel. The main fluid flows through the microchannel from the main inlet to the outlet, while the second fluid is injected through the pillar as two small jets at its upstream corners. For different values of the Reynolds number, intensity ratio between the jets and the main channel stream and jets injection angle, the authors have conducted several numerical simulations to characterize both the mixing efficiency and the required input power to make the fluids flow. The optimum configuration has been revealed for high values of the Reynolds number, low intensity ratios, and high injection angles. Thanks to vortex shedding and the corresponding downstream oscillations, a mixing efficiency of around 90% can be reached. The worst mixing efficiency is obtained for a configuration without vortex shedding, having a mixing efficiency of only around 2%.