Manufacturing Processes
Mahdi Moghimi; Naeem Jalali
Abstract
Micromixer is a significant component of microfluidics particularly in lab-on-chip applications so that there has been a growing need for design and fabrication of micromixers with a shorter length and higher efficiency. Despite most of the passive micromixers that suffer from long mixing path and complicated ...
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Micromixer is a significant component of microfluidics particularly in lab-on-chip applications so that there has been a growing need for design and fabrication of micromixers with a shorter length and higher efficiency. Despite most of the passive micromixers that suffer from long mixing path and complicated geometry to increase the efficiency, our novel design suggests a highly efficient micromixer while taking advantage of having a short length. The novelty of our work stems from utilizing all three mixing techniques of injection, recombination, and zigzag mixing resulting in benefits such as multi-flow lamination and flow resistance reduction in microscale. Moreover, the contraction and expansion of the microchannel width improve mixing. The present work deals with the parametric study, numerical simulation, as well as experimental tests and characterization of small planar passive micromixer. The high mixing efficiency yield of 98.02 was obtained with the length of only 1857.8 microns which shows good agreement in comparison with numerical simulation.
Hydraulic and Pneumatic Systems
Mahdi Moghimi
Abstract
Using experimental models along with conducting numerical analysis have been widely used in performance recognition and optimization of hydraulic equipments. Numerical modeling has lower cost rather than experimental one; however practical tests are commonly used because of the hydraulic structure importance ...
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Using experimental models along with conducting numerical analysis have been widely used in performance recognition and optimization of hydraulic equipments. Numerical modeling has lower cost rather than experimental one; however practical tests are commonly used because of the hydraulic structure importance especially in dams. Meanwhile numerical methods could be used for future designs through validating numerical models. In this paper, volume of fluid method, VOF, has been employed to simulate the free surface flow at the dam bottom outlet form bell mouth section up to the downstream channel. Since the flow through the gates has high Reynolds number, the standard k-ε and also Reynolds Stress Model, RSM, turbulence models is used and the results compared. The discharge coefficient and the ventilated air velocity through the vents is computed numerically and compared with the experimental data. Comparison between the experimental data and numerical simulation results shows good compatibility, especially in RSM turbulence model rather than k-ε turbulence model. The results show that the maximum error percentage in simulation of the discharge coefficient and the ventilated air velocity is 9% and 3% respectively.
