Numerical Simulation Based On Finite Element Theory Of Electroosmotic Flow In Micro Channels

The application of microfiuidic devices has been grown rapidly in many fields including disease diagnoses, medicine screening and environmental monitoring. As a result higher request of research about microfluidic arises. Microfluidic devices can offer many advantages such as small volume, multi-parameter of high tunable accuracy, reduced reagent consumption, shorter analysis time, and lower hardware cost. Some important affects on movement of microfluidic which are paid close attention to are ignored in macro scale.This article has discussed the elementary theory of the electroosmotic flow forming, induced the electric field and the flow field coupling field governing equation, and studied the influence of triangle surface roughness to the electroosmotic flow in circular cross-section micro channels, and the influence of the zeta electric potential and the micro channel section shape to the micro mixing influence using the multi-physical field analysis software.The main research results and the innovation in the article lie in:The influence mechanism of triangle surface roughness on electroosmotic flow in microchannels with circular cross-section is studied by the finite element simulation. The geometries of the surface roughness unit is modeled by triangular and the effects are analyzed when the microchannels both sides existence hindrance pressure. The results show that the section speed of flow reduces first and increases then when wall surface roughness width and gap increase in the micro channel. Section speed of flow reduces along with the relative roughness increase non-linearity and the tendency to change reduces. The line slope of pressure to the section speed reduces which means section speed of flow is not easily influenced by the pressure as relative roughness increases. This provides the instruction for precise control of the micro fluidic caused by electroosmotic flow.Two-dimensional micro mix driven by electroosmotic flow was studied by finite element simulation and mixes speed of microchannels with unified zeta potential of the wall surface and the polar opposite one was contrasted. Relation between the section shape of the microchannel and the speed of mixing is cleared when the wall surface has the polar opposite zeta potential. The results show that section mixing speed of microchannel whose wall surface with unified zeta potential is more high than the one with polar opposite wall surface zeta potential. Mixing speed of microchannel with homolographic rectangle section fast increases and then drops andante when the ratio of height and width increases. In microchannel of isosceles trapezoid section the speed of mixing first ascends rapidly along with the increment of height and then decreases slowly, arrived highest value when ratio of height and width is 1/6. It offers one kind of new way for the micro mixer design.