Research On The Characteristics Of Mixing And Separation In Microchannel Flow

The flow and mass transfer phenomenon in the microfluidic chips was studied in this thesis with the help of the numerical simulation method. In addition, the separation and mixing encountered in the microfluidics chip were in-depth analyzed and discussed. Some of the conclusions take certain guiding role for the design of microfluidic chips.In this paper, the development of microfluidic technology was comprehensive stated. Through the comparative analysis of static mixer and dynamic mixer, the impacts of microchannel configuration and microchannel surface characteristics on the flow field and chemical reactions were studied. Laminar and diffusion effect play important role for the microfluidic chip.Based on the theory of microfluid mechanics and the micro-electromechanical system, the regional division of fluid model was introduced. The microchannel advection-diffusion equation and the boundary conditions, and also the electroosmotic flow equation and the boundary conditions for the analysis of the microchannel flow were proposed.This paper introduces computer simulation methods for the microchannel flow field, that is the finite difference method and the finite volume method. The corresponding border approach was also given. The SIMPLE method for the solution of coupling physical variables was introduced. For the current microfluidic chip processing method and the structure, the measurement technology of fluid parameters in microchannel was introduced and analyzed.Based on the electrophoresis and separation in the bending microchannel we proposed the mathematical model for electroosmotic flow fields and the passive samples particles. Combined with the microchannel configuration, the sample discrete rate, symmetric rate and surface charge distribution, optimization parameters and optimize rules were proposed. Flow fields and the sample particle distribution were calculated under different circumstances. For the mixing of samples liquid and reference solution in the microchannel, the mixing efficiency indicator was proposed based on the section uniformity of the mass fraction. The S-type microchannel flow field has been calculated, the impact of concentration at the location imports and inlet velocity on the mixing efficiency was also studied. Calculation and analysis were carried out for the effects of the speed difference of the sample and reference in the imports. We compared the mixing characteristics on several cross-sections in the microchannel. The reasons for the differences of the concentration distribution in the different cross-sections were discussed and analyzed.Comparison method of mixing characteristics was proposed for the fluid mixing in the serpentine microchannel with three-dimensional structure. Using numerical methods, we studied the impact of inlet velocity and structure geometric parameters on the efficiency. In the same basic parameters the mixing efficiency of serpentine mixer, linear and planar mixer was compared. That supplied an important basis for the design of efficient micromixer.