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Flow Characteristics of the Entrance Region with Roughness Effect within Rectangular Microchannels

We conducted systematic numerical investigations of the flow characteristics within the entrance region of rectangular microchannels. The effects of the geometrical aspect ratio and roughness on entrance lengths were analyzed. The incompressible laminar Navier–Stokes equations were solved using fini...

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Autores principales: Li, Haiwang, Li, Yujia, Huang, Binghuan, Xu, Tiantong
Formato: Online Artículo Texto
Lenguaje:English
Publicado: MDPI 2019
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7019266/
https://www.ncbi.nlm.nih.gov/pubmed/31881751
http://dx.doi.org/10.3390/mi11010030
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author Li, Haiwang
Li, Yujia
Huang, Binghuan
Xu, Tiantong
author_facet Li, Haiwang
Li, Yujia
Huang, Binghuan
Xu, Tiantong
author_sort Li, Haiwang
collection PubMed
description We conducted systematic numerical investigations of the flow characteristics within the entrance region of rectangular microchannels. The effects of the geometrical aspect ratio and roughness on entrance lengths were analyzed. The incompressible laminar Navier–Stokes equations were solved using finite volume method (FVM). In the simulation, hydraulic diameters ([Formula: see text]) ranging from 50 to 200 µm were studied, and aspect ratios of 1, 1.25, 1.5, 1.75, and 2 were considered as well. The working fluid was set as water, and the Reynolds number ranged from 0.5 to 100. The results showed a good agreement with the conducted experiment. Correlations are proposed to predict the entrance lengths of microchannels with respect to different aspect ratios. Compared with other correlations, these new correlations are more reliable because a more practical inlet condition was considered in our investigations. Instead of considering the influence of the width and height of the microchannels, in our investigation we proved that the critical role is played by the aspect ratio, representing the combination of the aforementioned parameters. Furthermore, the existence of rough elements obviously shortens the entrance region, and this effect became more pronounced with increasing relative roughness and Reynolds number. A similar effect could be seen by shortening the roughness spacing. An asymmetric distribution of rough elements decreased the entrance length compared with a symmetric distribution, which can be extrapolated to other irregularly distributed forms.
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spelling pubmed-70192662020-03-04 Flow Characteristics of the Entrance Region with Roughness Effect within Rectangular Microchannels Li, Haiwang Li, Yujia Huang, Binghuan Xu, Tiantong Micromachines (Basel) Article We conducted systematic numerical investigations of the flow characteristics within the entrance region of rectangular microchannels. The effects of the geometrical aspect ratio and roughness on entrance lengths were analyzed. The incompressible laminar Navier–Stokes equations were solved using finite volume method (FVM). In the simulation, hydraulic diameters ([Formula: see text]) ranging from 50 to 200 µm were studied, and aspect ratios of 1, 1.25, 1.5, 1.75, and 2 were considered as well. The working fluid was set as water, and the Reynolds number ranged from 0.5 to 100. The results showed a good agreement with the conducted experiment. Correlations are proposed to predict the entrance lengths of microchannels with respect to different aspect ratios. Compared with other correlations, these new correlations are more reliable because a more practical inlet condition was considered in our investigations. Instead of considering the influence of the width and height of the microchannels, in our investigation we proved that the critical role is played by the aspect ratio, representing the combination of the aforementioned parameters. Furthermore, the existence of rough elements obviously shortens the entrance region, and this effect became more pronounced with increasing relative roughness and Reynolds number. A similar effect could be seen by shortening the roughness spacing. An asymmetric distribution of rough elements decreased the entrance length compared with a symmetric distribution, which can be extrapolated to other irregularly distributed forms. MDPI 2019-12-25 /pmc/articles/PMC7019266/ /pubmed/31881751 http://dx.doi.org/10.3390/mi11010030 Text en © 2019 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/).
spellingShingle Article
Li, Haiwang
Li, Yujia
Huang, Binghuan
Xu, Tiantong
Flow Characteristics of the Entrance Region with Roughness Effect within Rectangular Microchannels
title Flow Characteristics of the Entrance Region with Roughness Effect within Rectangular Microchannels
title_full Flow Characteristics of the Entrance Region with Roughness Effect within Rectangular Microchannels
title_fullStr Flow Characteristics of the Entrance Region with Roughness Effect within Rectangular Microchannels
title_full_unstemmed Flow Characteristics of the Entrance Region with Roughness Effect within Rectangular Microchannels
title_short Flow Characteristics of the Entrance Region with Roughness Effect within Rectangular Microchannels
title_sort flow characteristics of the entrance region with roughness effect within rectangular microchannels
topic Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7019266/
https://www.ncbi.nlm.nih.gov/pubmed/31881751
http://dx.doi.org/10.3390/mi11010030
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