Modeling for Fluid Mixing in Passive Micromixers Using the Vortex Index

Abstract

The present paper addresses the effects of molecular diffusion and the vorticity of microchannel flows on mixing in passive micromixers, which are essential components of a microfluidic chip. A model that can predict the mixing performance of passive micromixers is developed based on the physical characteristics of mixing such as the Peclet number and the vortex index that is newly defined in this paper. In order to investigate the flow physics in the passive mixers, we performed numerical simulations for a wide range of Peclet numbers and Reynolds numbers. The model is found to be able to accurately predict the mixing performance of passive mixers without solving the coupled, complex diffusion and momentum equations.