Abstract
In recent years, microfluidic devices have been used to handle more concentrated solutions. In these cases, the influence of the viscosity of the solution upon flow and diffusion in the microfluidic device cannot be neglected. In this study, hydrodynamic and diffusion behaviour of two liquids of different viscosity in contact in a double Y type microfluidic device were investigated. The relationship between the concentration and flow rate at the outlet of microfluidic device and the viscosity ratio of the solution and solvent was measured. CFD was used to predict the flow in the microfluidic device. Diffusion of the Co2+-DEHPA complex in the micro-fluidic device was also investigated.When the two fluids with different viscosity were pumped to a channel at the same flow rate, the fluid with high viscosity flowed into the low viscosity side. The cross-section of the low viscosity fluid became narrow, the velocity increased, and the interface of two fluids moved to the low viscosity fluid side. When a viscosity ratio was large, the movement of the interface and the difference of velocity were large. Numerical simulation reproduced the influence of the viscosity ratio on the velocity and con-centration distribution movement of the interface can be prevented by in-creasing the relative flow rate of low viscosity fluid, this is also repro-duced by numerical simulations.
