scholarly journals Multiple temperature model of nonlinear coupled constitutive relations for hypersonic diatomic gas flows

AIP Advances ◽  
2020 ◽  
Vol 10 (5) ◽  
pp. 055023
Author(s):  
Zhenyu Yuan ◽  
Zhongzheng Jiang ◽  
Wenwen Zhao ◽  
Weifang Chen
Keyword(s):  
Constitutive Relations ◽  
Gas Flows ◽  
Temperature Model ◽  
Diatomic Gas

A Parallel DSMC Investigation of Monatomic/Diatomic Gas Flows in a Micro/Nano Cavity

2013 ◽  
Vol 63 (4) ◽  
pp. 305-325 ◽  
Author(s):  
Alireza Mohammadzadeh ◽  
Ehsan Roohi ◽  
Hamid Niazmand
Keyword(s):  
Gas Flows ◽  
Diatomic Gas

scholarly journals On the modelling of isothermal gas flows at the microscale

2008 ◽  
Vol 604 ◽  
pp. 235-261 ◽  
Author(s):  
DUNCAN A. LOCKERBY ◽  
JASON M. REESE
Keyword(s):  
Boundary Conditions ◽  
Constitutive Relations ◽  
Navier Stokes ◽  
Test Case ◽  
Gas Flows ◽  
Hydrodynamic Models ◽  
Slip Boundary ◽  
Knudsen Numbers ◽  
Isothermal Gas ◽  
Non Equilibrium

This paper makes two new propositions regarding the modelling of rarefied (non-equilibrium) isothermal gas flows at the microscale. The first is a new test case for benchmarking high-order, or extended, hydrodynamic models for these flows. This standing time-varying shear-wave problem does not require boundary conditions to be specified at a solid surface, so is useful for assessing whether fluid models can capture rarefaction effects in the bulk flow. We assess a number of different proposed extended hydrodynamic models, and we find the R13 equations perform the best in this case.Our second proposition is a simple technique for introducing non-equilibrium effects caused by the presence of solid surfaces into the computational fluid dynamics framework. By combining a new model for slip boundary conditions with a near-wall scaling of the Navier--Stokes constitutive relations, we obtain a model that is much more accurate at higher Knudsen numbers than the conventional second-order slip model. We show that this provides good results for combined Couette/Poiseuille flow, and that the model can predict the stress/strain-rate inversion that is evident from molecular simulations. The model's generality to non-planar geometries is demonstrated by examining low-speed flow around a micro-sphere. It shows a marked improvement over conventional predictions of the drag on the sphere, although there are some questions regarding its stability at the highest Knudsen numbers.

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