TJ375 : Numerical solution of induced charge electrokinetic in a microchannel with Non-Newtonian Fluid
Thesis > Central Library of Shahrood University > Mechanical Engineering > MSc > 2015
Authors:
Mahsa Mostafavi [Author], Mohsen Nazari[Supervisor]
Abstarct: In this study, mixing of non-Newtonian fluids in a micro channel with conductive hurdles and flow control of non-Newtonian fluids are investigated numerically. These studies are baxsed on the concept of induced electro-kinetic phenomena. In comparison with classic electro-kinetic, in the induced electro-kinetic, induced charges on the conductive surfaces are not constant. In other word, the induced charges are functions of electric field; therefore, the electro-osmotic velocity has non-linear correlation with of the electric field. Electro-kinetic with induced charges contains special properties which can be used in development of lab on a chip in microfluidic field. For this aim, Finite Element Method (FEM) is used for simulation of flow and concentration fields. In this problem, triangular mesh is created to discretize the computational domain. To validate the presented model, a comparison between Newtonian flow in the presence of the conductive hurdles (available in the literature) and present model is implemented. In the first section of results, in mixing of two Newtonian fluids, the effects of hurdles position, hurdles height, hurdles angles and electric field strength on mixing performance are investigated. When electric field is applied, the vortices are generated around the conductive hurdles. The Results showed that when position and angles of hurdles are constant, by increasing the ratio of hurdles height to the channel width, the mixing efficiency is increased; which is mainly due to the enlarged vortices around the hurdles. In this research, for the first time, mixing of two non-Newtonian fluids (i.e. Carreau model) in presence of two conducting triangle hurdles is analyzed by using of induced electro-kinetic concept. By analyzing the effect of non-Newtonian index (i.e. n) on the performance of mixing, it was observed that decreasing of n leads to increase in mixing efficiency. When fluid becomes more shear-thinning and the length of generated vortex is enlarged؛ therefore the rate of mixing in the micro channel is increased. Finally, effect of electric field strength, n-index of non-Newtonian fluid and angle of hurdles on flow control in micro channel with conductive asymmetrical hurdles were studied. The obtained results showed when angle of hurdles in downstream is close to angle of hurdles in upstream, larger critical electric field strength is needed to achieve a zero flow rate.
Keywords:
#mixing-flow control- non-Newtonian fluid- induced charge -electrokinetics(ICEK) Link
Keeping place: Central Library of Shahrood University
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