Influence of Surface Roughness on Micro-Scale Rarefied Gas Flows

2008 ◽  
Author(s):  
O. A. Aksenova ◽  
L. A. Khalidov ◽  
Takashi Abe
Keyword(s):  
Surface Roughness ◽  
Rarefied Gas ◽  
Gas Flows ◽  
Micro Scale ◽  
Rarefied Gas Flows

Simulation of Rarefied Gas Flows in MEMS/NEMS Using a Molecular Method

2009 ◽  
Author(s):  
Hadi Ghezel Sofloo ◽  
Reza Ebrahimi ◽  
Alireza Shams
Keyword(s):  
Rarefied Gas ◽  
Molecular Model ◽  
Direct Simulation Monte Carlo ◽  
Boltzmann Distribution ◽  
Gas Flows ◽  
Air Bearing ◽  
Molecular Collision ◽  
Micro Scale ◽  
Rarefied Gas Flows ◽  
Slider Air Bearing

In this work, the development of a two-dimensional Direct Simulation Monte Carlo (DSMC) Program for pressure boundaries using unstructured cells and its applications to typical micro-scale gas flows are described. For the molecular collision kinetics, variable hard sphere molecular model and no time counter collision sampling scheme have been used. Applications to micro-scale gas flows include micro-nozzel, nano channel and slider air bearing. The aim is to further test the treatment of pressure boundaries. For slider air bearing gas flows of the computer hard drive, the simulated gas pressures, at different rotating speeds, have a very good agreement with previous studies. The applicability of the treatment of pressure boundaries using the equilibrium Maxwell-Boltzmann distribution function was discussed in terms of the magnitude of the local Knudsen number at the pressure boundary for micro-nozzles and slider air bearing applications.

Shock polar investigation in supersonic rarefied gas flows over a circular cylinder

2021 ◽  
Vol 33 (5) ◽  
pp. 052006
Author(s):  
Hassan Akhlaghi ◽  
Ehsan Roohi ◽  
Abbas Daliri ◽  
Mohammad-Reza Soltani
Keyword(s):  
Circular Cylinder ◽  
Rarefied Gas ◽  
Gas Flows ◽  
Rarefied Gas Flows

scholarly journals Rarefied gas flows through meshes and implications for atmospheric measurements

2001 ◽  
Vol 19 (5) ◽  
pp. 563-569 ◽  
Author(s):  
J. Gumbel
Keyword(s):  
Middle Atmosphere ◽  
Rarefied Gas ◽  
Direct Simulation Monte Carlo ◽  
Atmospheric Composition ◽  
Gas Flows ◽  
Atmospheric Measurements ◽  
Rarefied Gas Flows ◽  
Flow Disturbances ◽  
Composition And Structure ◽  
Compression Effects

Abstract. Meshes are commonly used as part of instruments for in situ atmospheric measurements. This study analyses the aerodynamic effect of meshes by means of wind tunnel experiments and numerical simulations. Based on the Direct Simulation Monte Carlo method, a simple mesh parameterisation is described and applied to a number of representative flow conditions. For open meshes freely exposed to the flow, substantial compression effects are found both upstream and downstream of the mesh. Meshes attached to close instrument structures, on the other hand, cause only minor flow disturbances. In an accompanying paper, the approach developed here is applied to the quantitative analysis of rocket-borne density measurements in the middle atmosphere.Key words. Atmospheric composition and structure (instruments and techniques; middle atmosphere – composition and chemistry)

scholarly journals An open source, parallel DSMC code for rarefied gas flows in arbitrary geometries

2010 ◽  
Vol 39 (10) ◽  
pp. 2078-2089 ◽  
Author(s):  
T.J. Scanlon ◽  
E. Roohi ◽  
C. White ◽  
M. Darbandi ◽  
J.M. Reese
Keyword(s):  
Open Source ◽  
Rarefied Gas ◽  
Gas Flows ◽  
Rarefied Gas Flows ◽  
Arbitrary Geometries
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