Electrodynamic Transport Properties Of Micro-nano Channel Of Viscoelastic Fluid

With the progress and integration of multi-disciplines,microfluidic chips have more and more extensive applications.In the shipping industry,from rapid and immediate diagnosis of seafarers'diseases(Point-of-Care Testing),to automatic signal transmission and desalination has a broad application prospect.In addition,microfluidic chips are used in the sensing and detection of nanoparticles,the operation and reaction of analytical chemistry,the encryption and decryption of information,future military communications and so on.As we all know,from the point of the microfluidic device laboratory based on chip,the electroosmotic activity has been well studied and recorded.Therefore,the research on the electrodynamic transport characteristics in micro-nanofluidic devices has fundamental theoretical basis and practical application.In this work,based on the Open FOAM open source toolkit and FVM(finite volume method),a variety of constitutive models are applied to the electrically driven flow with elastic characteristics,and the electrodynamic coupling model of non-Newtonian fluid is developed.The LCR method(LCR,Log Conformation Reformulation)is used to solve the high Weissenberg problem caused by elasticity in viscoelastic fluid flow.The main research work is as follows:(1)The constitutive equation of non-Newtonian fluid and the characteristics of micro-nano-scale flow are discussed,and the development of numerical simulation of viscoelastic flow is summarized.the rheological properties,constitutive equation and the theoretical background of electrodynamic transport are introduced,as well as the phenomena of EDL(electric double layer)overlap,EOF(electroosmotic flow),ion ICP(concentration polarization)and so on.(2)Based on the sudden contraction and expansion flow,the elastic-eddy current effect are solved,the different shrinkage ratio A,voltage V and surface charge density?_w are analyzed,and the internal mechanism of pressure driving is different from that widely studied macroscopically.(3)The LPTT model is used to fit the constitutive characteristics of viscoelastic fluid.Based on the coupling of PNP and N-S equations,the EOF in a long straight channel is analyzed.Based on the derived dimensionless number k H(the ratio of channel height to the thickness of electric double layer),the effects of extensible parameters,viscosity ratio A and Wi number on the velocity and the stress?_xy near the wall are discussed.(4)Considering the micro-nano interconnected system under the overlap of electric double layer,using Oldroyd-B to fit the biological fluid characteristics,fully considering the protonation/deprotonation reaction near the wall and the introduction of pH,the fluid viscoelastic properties and the rules of ion current I,conductivity G,ion concentration distribution,ICP phenomenon and ion selectivity S_pore under the influence of pH were studied.