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Velocity Measurements in Channel Gas Flows in the Slip Regime by means of Molecular Tagging Velocimetry

Direct measurements of the slip velocity in rarefied gas flows produced by local thermodynamic non-equilibrium at the wall represent crucial information for the validation of existing theoretical and numerical models. In this work, molecular tagging velocimetry (MTV) by direct phosphorescence is app...

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Autores principales: Fratantonio, Dominique, Rojas-Cárdenas, Marcos, Barrot, Christine, Baldas, Lucien, Colin, Stéphane
Formato: Online Artículo Texto
Lenguaje:English
Publicado: MDPI 2020
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7230473/
https://www.ncbi.nlm.nih.gov/pubmed/32252354
http://dx.doi.org/10.3390/mi11040374
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author Fratantonio, Dominique
Rojas-Cárdenas, Marcos
Barrot, Christine
Baldas, Lucien
Colin, Stéphane
author_facet Fratantonio, Dominique
Rojas-Cárdenas, Marcos
Barrot, Christine
Baldas, Lucien
Colin, Stéphane
author_sort Fratantonio, Dominique
collection PubMed
description Direct measurements of the slip velocity in rarefied gas flows produced by local thermodynamic non-equilibrium at the wall represent crucial information for the validation of existing theoretical and numerical models. In this work, molecular tagging velocimetry (MTV) by direct phosphorescence is applied to argon and helium flows at low pressures in a 1-mm deep channel. MTV has provided accurate measurements of the molecular displacement of the gas at average pressures of the order of 1 kPa. To the best of our knowledge, this work reports the very first flow visualizations of a gas in a confined domain and in the slip flow regime, with Knudsen numbers up to 0.014. MTV is cross-validated with mass flowrate measurements by the constant volume technique. The two diagnostic methods are applied simultaneously, and the measurements in terms of average velocity at the test section are in good agreement. Moreover, preliminary results of the slip velocity at the wall are computed from the MTV data by means of a reconstruction method.
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spelling pubmed-72304732020-05-22 Velocity Measurements in Channel Gas Flows in the Slip Regime by means of Molecular Tagging Velocimetry Fratantonio, Dominique Rojas-Cárdenas, Marcos Barrot, Christine Baldas, Lucien Colin, Stéphane Micromachines (Basel) Article Direct measurements of the slip velocity in rarefied gas flows produced by local thermodynamic non-equilibrium at the wall represent crucial information for the validation of existing theoretical and numerical models. In this work, molecular tagging velocimetry (MTV) by direct phosphorescence is applied to argon and helium flows at low pressures in a 1-mm deep channel. MTV has provided accurate measurements of the molecular displacement of the gas at average pressures of the order of 1 kPa. To the best of our knowledge, this work reports the very first flow visualizations of a gas in a confined domain and in the slip flow regime, with Knudsen numbers up to 0.014. MTV is cross-validated with mass flowrate measurements by the constant volume technique. The two diagnostic methods are applied simultaneously, and the measurements in terms of average velocity at the test section are in good agreement. Moreover, preliminary results of the slip velocity at the wall are computed from the MTV data by means of a reconstruction method. MDPI 2020-04-02 /pmc/articles/PMC7230473/ /pubmed/32252354 http://dx.doi.org/10.3390/mi11040374 Text en © 2020 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
Fratantonio, Dominique
Rojas-Cárdenas, Marcos
Barrot, Christine
Baldas, Lucien
Colin, Stéphane
Velocity Measurements in Channel Gas Flows in the Slip Regime by means of Molecular Tagging Velocimetry
title Velocity Measurements in Channel Gas Flows in the Slip Regime by means of Molecular Tagging Velocimetry
title_full Velocity Measurements in Channel Gas Flows in the Slip Regime by means of Molecular Tagging Velocimetry
title_fullStr Velocity Measurements in Channel Gas Flows in the Slip Regime by means of Molecular Tagging Velocimetry
title_full_unstemmed Velocity Measurements in Channel Gas Flows in the Slip Regime by means of Molecular Tagging Velocimetry
title_short Velocity Measurements in Channel Gas Flows in the Slip Regime by means of Molecular Tagging Velocimetry
title_sort velocity measurements in channel gas flows in the slip regime by means of molecular tagging velocimetry
topic Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7230473/
https://www.ncbi.nlm.nih.gov/pubmed/32252354
http://dx.doi.org/10.3390/mi11040374
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