Numerical Investigation of Fluid Mixing in a Micro-Channel Mixer with Two Rotating Stirrers by Using the Incompressible SPH Method

Fluid mixing is a crucial and challenging process for microfluidic systems, which are widely used in biochemical processes. Because of their fast performance, active micromixers that use stirrer blades are considered for biological applications. In the present study, by using a robust and convenient Incompressible Smoothed Particle Hydrodynamics (ISPH) method, miscible mixing within a two-blade micromixer is investigated. The problem discussed herein is represented by an active micromixer comprising two stir-bars that rotate to mix the fluids. Because of its Lagrangian nature, Smoothed Particle Hydrodynamics is an appropriate and convenient method for simulating moving boundary problems and tracking the particles in the mixing process. Previous investigations have been carried out for mixing flow for a low Schmidt number. However, a low Schmidt number is barely applicable for liquid mixing. Hence, in the present study, the Schmidt number is considered to be Sc=1000. The present results show that the two-blade micro-channel mixer considerably improves the mixing rate in comparison with the one-blade micro-channel mixer.