Effects of planar inlet plenums on the hydrodynamically developing flows in rectangular microchannels of complementary aspect ratios |
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Authors: | Sang-Youp Lee Jaesung Jang Steven T Wereley |
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Affiliation: | 1. Microfluidics Laboratory, School of Mechanical Engineering, Purdue University, Room 175, 585 Purdue Mall, West Lafayette, IN, 47907-2088, USA 2. Department of Basic Medical Sciences, Bindley Biosciences Center, Purdue University Cytometry Laboratory, West Lafayette, IN, 47907, USA 3. Laboratory of Integrated Biomedical Micro/Nanotechnology and Applications, Birck Nanotechnology Center, Bindley Biosciences Center, School of Electrical and Computer Engineering, Purdue University, West Lafayette, IN, 47907, USA
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Abstract: | The effects of planar inlet plenum geometry on the developing flow fields in two rectangular microchannels of reciprocal aspect
ratios (H/W ∼2.75 and ∼0.40) were investigated for Re
D
= 1–100 using micro particle image velocimetry (μPIV). These two microchannels were made by a precision sawing and silicon
microfabrication techniques. Both the velocity profiles and centerline velocity developments were clearly resolved and extracted
along the axial distance from μPIV results. The entrance lengths were found from the centerline velocities using a decaying
exponential fitting function where the centerline velocity reaches 99% of the fully developed centerline velocity. The proposed
fitting function showed excellent agreement with the experimental results. The planar plenum was shown to cause an upstream
predevelopment resulting in the significant reductions in the entrance lengths. Two entrance length correlations were proposed
in the forms of Atkinson et al.’s (AIChE J 15:548–553, 1969) and Chen’s (J Fluids Eng 95:153–158, 1973) correlations. The proposed entrance length correlations showed that acquired constant portion and slope of the entrance
lengths showed 23–27 and 70–81% reductions for H/W = 2.75 while the entrance length correlation for H/W = 0.40 showed 69–73% increase and 41–63% decrease in the constant portion and slope, respectively. |
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Keywords: | Entrance length Rectangular microchannel Hydrodynamically developing flow Aspect ratio of rectangular microchannel Micro particle image velocimetry |
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