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Open AccessArticle

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

1
Los Alamos National Laboratories, Physics Division, Los Alamos, NM 87545, USA
2
Institut Clément Ader (ICA), Université de Toulouse CNRS, INSA, ISAE-SUPAERO, Mines-Albi, UPS, 31400 Toulouse, France
*
Author to whom correspondence should be addressed.
Micromachines 2020, 11(4), 374; https://doi.org/10.3390/mi11040374
Received: 5 March 2020 / Revised: 30 March 2020 / Accepted: 30 March 2020 / Published: 2 April 2020
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. View Full-Text
Keywords: rarefied gas; slip velocity; channel flow; molecular tagging velocimetry rarefied gas; slip velocity; channel flow; molecular tagging velocimetry
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MDPI and ACS Style

Fratantonio, D.; Rojas-Cárdenas, M.; Barrot, C.; Baldas, L.; Colin, S. Velocity Measurements in Channel Gas Flows in the Slip Regime by means of Molecular Tagging Velocimetry. Micromachines 2020, 11, 374.

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