Improvement of rectification effects in diffuser/nozzle structures with viscoelastic fluids |
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| Authors: | Nam-Trung Nguyen Yee-Cheong Lam Soon-Seng Ho and Cassandra Lee-Ngo Low |
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| Institution: | 1School of Mechanical and Aerospace Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798, Singapore;2School of Electronics and Electrical Engineering, Singapore Polytechnic, 500 Dover Road, Singapore 139651, Singapore |
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| Abstract: | This paper reports the improvement of rectification effects in diffuser∕nozzle structures with viscoelastic fluids. Since rectification in a diffuser∕nozzle structure with Newtonian fluids is caused by inertial effects, micropumps based on this concept require a relatively high Reynolds numbers and high pumping frequencies. In applications with relatively low Reynolds numbers, anisotropic behavior can be achieved with viscoelastic effects. In our investigations, a solution of dilute polyethylene oxide was used as the viscoelastic fluid. A microfluidic device was fabricated in silicon using deep reactive ion etching. The microfluidic device consists of access ports for pressure measurement, and a series of ten diffuser∕nozzle structures. Measurements were carried out for diffuser∕nozzle structures with opening angles ranging from 15° to 60°. Flow visualization, pressure drop and diodicity of de-ionized water and the viscoelastic fluid were compared and discussed. The improvement of diodicity promises a simple pumping concept at low Reynolds numbers for lab-on-a-chip applications. |
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