Numerical analysis of knudsen number of helium flow through gas-focused liquid sheet micro-nozzle

Kovačič, Krištof (author), Bajt, Saša (author), Šarler, Božidar (author)

This work aims to verify whether the continuum mechanics assumption holds for the numerical simulation of a typical sample delivery system in serial femtosecond crystallography (SFX). Knudsen numbers were calculated based on the numerical simulation results of helium flow through the gas-focused liquid sheet nozzle into the vacuum chamber, representing the upper limit of Knudsen number for such systems. The analysed flow is considered steady, compressible, and laminar. The numerical results are mesh-independent, with a Grid Convergence Index significantly lower than 1% for global and local analysis. This study is based on an improved definition of the numerical Knudsen number: a combination of the cell Knudsen number and the physical Knudsen number. In the analysis, no-slip boundary and low-pressure boundary slip conditions are compared. No significant differences are observed. This study justifies using computational fluid dynamics (CFD) analysis for SFX sample delivery systems based on the assumption of continuum mechanics.

• Language: English
• Keywords: Knudsen number, compressible hypersonic flow, vacuum, liquid sheet nozzle, sample delivery system, CFD
• Work type: Article
• Typology: 1.01 - Original Scientific Article
• Organization: FS - Faculty of Mechanical Engineering
• Publication status: Published
• Publication version: Version of Record
• Year: 2024
• Number of pages: 15 str.
• Numbering: Vol. 9, iss. 12, [art. no.] 273
• PID: 20.500.12556/RUL-165095
• UDC: 532
• ISSN on article: 2311-5521
• DOI: 10.3390/fluids9120273
• COBISS.SI-ID: 216132867
• Publication date in RUL: 22.11.2024

Record is a part of a journal

• Title: Fluids
• Shortened title: Fluids
• Publisher: MDPI AG
• ISSN: 2311-5521
• COBISS.SI-ID: 525935385

Licences

• License: CC BY 4.0, Creative Commons Attribution 4.0 International
• Link: http://creativecommons.org/licenses/by/4.0/
• Description: This is the standard Creative Commons license that gives others maximum freedom to do what they want with the work as long as they credit the author.