Effect of Cross Aspect Ratio on Flow in Diverging and Converging Microchannels

Duryodhan, V S and Singh, Shiv Govind and Agarwal, Anil (2017) Effect of Cross Aspect Ratio on Flow in Diverging and Converging Microchannels. Journal of Fluids Engineering, 139 (6). 061203. ISSN 0098-2202

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Aspect ratio is an important parameter in the study of flow through noncircular microchannel. In this work, three-dimensional numerical study is carried out to understand the effect of cross aspect ratio (height to width) on flow in diverging and converging microchannels. Three-dimensional models of the diverging and converging microchannels with angle: 2-14 deg, aspect ratio: 0.05-0.58, and Reynolds number: 130-280 are employed in the simulations with water as the working fluid. The effects of aspect ratio on pressure drop in equivalent diverging and converging microchannels are studied in detail and correlated to the underlying flow regime. It is observed that for a given Reynolds number and angle, the pressure drop decreases asymptotically with aspect ratio for both the diverging and converging microchannels. At small aspect ratio and small Reynolds number, the pressure drop remains invariant of angle in both the diverging and converging microchannels; the concept of equivalent hydraulic diameter can be applied to these situations. Onset of flow separation in diverging passage and flow acceleration in converging passage is found to be a strong function of aspect ratio, which has not been shown earlier. The existence of a critical angle with relevance to the concept of equivalent hydraulic diameter is identified and its variation with Reynolds number is discussed. Finally, the effect of aspect ratio on fluidic diodicity is discussed which will be helpful in the design of valveless micropump. These results help in extending the conventional formulae made for uniform cross-sectional channel to that for the diverging and converging microchannels.

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IITH Creators:
IITH CreatorsORCiD
Singh, Shiv Govindorcid.org/0000-0001-7319-879X
Item Type: Article
Uncontrolled Keywords: equivalent hydraulic diameter; area-varying channel; critical angle of divergence/convergence; diffuser; nozzle
Subjects: Physics > Mechanical and aerospace
Electrical Engineering > Electrical and Electronic
Divisions: Department of Electrical Engineering
Department of Mechanical & Aerospace Engineering
Depositing User: Team Library
Date Deposited: 13 Jun 2017 07:25
Last Modified: 29 Aug 2017 10:10
URI: http://raiith.iith.ac.in/id/eprint/3218
Publisher URL: https://doi.org/10.1115/1.4035945
OA policy: http://www.sherpa.ac.uk/romeo/issn/0098-2202/
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