Effect of micro-channel geometry on fluid flow and mixing

Naher, S., Orpen, D., Brabazon, D., Poulsen, C.R. & Morshed, M.M. (2010). Effect of micro-channel geometry on fluid flow and mixing. Simulation Modelling Practice and Theory, 19(4), pp. 1088-1095. doi: 10.1016/j.simpat.2010.12.008

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Understanding the flow fields at the micro-scale is key to developing methods of successfully mixing fluids for micro-scale applications. This paper investigates flow characteristics and mixing efficiency of three different geometries in micro-channels. The geometries of these channels were rectangular with a dimension of; 300 lm wide, 100 lm deep and 50 mm long. In first channel there was no obstacle and in the second channel there were rectangular blocks of dimension 300 lm long and 150 lmwide are placed in the flow fields with every 300 lm distance attaching along the channel wall. In the third geometry, there were 100 lm wide fins with 150_ angle which were placed at a distance of 500 lm apart from each other attached with the wall along the 50 mm channel. Fluent software of Computational Fluid Dynamics (CFD) was used to investigate the flow characteristics within these microfluidic model for three different geometries. A species 2D model was created for three geometries and simulations were run in order to investigate the mixing behavior of two different fluid with viscosity of water (1 mPa s). Models were only built to investigate the effect of geometry, therefore only one fluid with similar viscosity was used in these models. Velocity vector plots were used in the CFD analysis to visualise the fluid flow path. Mass fractions of fluid were used to analyse the mixing efficiency. Two different colours for water were used to simulate the effect of two different fluids. The results showed that the mixing behaviour strongly depended on the channel geometry when other parameters such as fluid inlet velocity, viscosity and pressure of fluids were kept constant. In two geometries lateral pressure and swirling vortexes were developed which provided better mixing results. Creation of swirling vortexes increased diffusion gradients which enhanced diffusive mixing.

Item Type: Article
Additional Information: © 2010, Elsevier. Licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International http://creativecommons.org/licenses/by-nc-nd/4.0/
Uncontrolled Keywords: Applied Mathematics; Computation Theory And Mathematics; Mechanical Engineering
Subjects: T Technology > TA Engineering (General). Civil engineering (General)
Divisions: School of Engineering & Mathematical Sciences > Engineering
URI: http://openaccess.city.ac.uk/id/eprint/14582

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