Measurements of the relative momentum accommodation coefficient for different gases with a viscosity vacuum gauge

Gronych, T.; Ulman, Radek; Peksa, L.; Řepa, P.

doi:10.1016/j.vacuum.2003.12.017

Cited by 31 publications

(12 citation statements)

References 11 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The former is based on the work by Gronych et al (2004), who have conducted experiments to find out that the tangential momentum accommodation coefficient increases as the molecular weight of the gas decreases. This may be related to the influence of gas species.…”

Section: Tablementioning

confidence: 99%

Effects of gas species on pressure dependence of thermophoretic velocity

Razali

Mori

Suzuki

et al. 2012

Journal of Aerosol Science

View full text Add to dashboard Cite

Section: Tablementioning

confidence: 99%

Effects of gas species on pressure dependence of thermophoretic velocity

Razali

Mori

Suzuki

et al. 2012

Journal of Aerosol Science

View full text Add to dashboard Cite

“…In most macroscopic applications, TMAC is generally assumed to be unity, expressing diffusive reflection on the surfaces. While in many higher Kn experiments [9][10][11][12][13][14][15][16] and molecular dynamics (MD) simulations [17][18][19][20][21][22][23][24][25], the TMAC was reported to be always less than unity. For a variety of gases (mostly noble gases) on metals, semiconductors, or even glass surfaces, the TMAC may be impacted by many factors, such as gas and wall materials [9][10][11][12][13][14][15][16][20][21][22][23][24], incident gas angle and energy [9,11,[17][18][19]21], surface roughness [23], wall temperature [9,11,[17][18][19][21][22][23] and adsorbed layers or gas molecules adsorption [13,…”

Section: Introductionmentioning

confidence: 99%

Effect of gas adsorption on momentum accommodation coefficients in microgas flows using molecular dynamic simulations

Sun

2008

Molecular Physics

View full text Add to dashboard Cite

The tangential momentum accommodation coefficient (TMAC), usually used in slip boundary conditions in micro-gas flows, is reported to be always less than unity and greatly influenced by temperature and the strength of gas-wall interactions. According to the definitions of accommodation coefficients, a proper statistical algorithm in non-equilibrium molecular dynamics method was described and verified. In planar Poiseuille gas flow in a smooth microchannel, the TMAC were calculated considering both the effects of temperature and gas-wall interaction. In the simulation processes, more gas molecules began to be adsorbed near walls under the condition of stronger gas-wall interaction and lower temperature. The gas adsorption resulted in a longer gas-wall interaction time so that the TMAC increased. While the gas-wall interaction became much stronger, more and more gas molecules were adsorbed to form an explicit layer above the wall. The full coverage of gas molecules on the wall prevented further adsorption; therefore the TMAC did not keep on increasing as the interaction strength continued to increase. Meanwhile, the normal momentum accommodation coefficient (NMAC) was also calculated according to the definition. In the isothermal flow, the average gas momentum normal to the wall was in complete accommodation with the wall, and the NMAC was almost unity in smooth micro channels.

show abstract

“…Note that it can be easily checked that, for a flat wall (i.e. for an interaction potential V(x, z) = V(z)), the boundary conditions (16) reduces to the classical specular reflection.…”

Section: New Boundary Conditions For the Boltzmann Equationmentioning

confidence: 99%

“…Then, as we indicated above, for a flat wall the boundary condition is the usual specular reflection. For a periodic rough wall the boundary condition introduced in 4 is given by (16)(17).…”

Section: Implementation Of Mlbc In a Dvm Contextmentioning

confidence: 99%

Nanoscale roughness effect on Maxwell-like boundary conditions for the Boltzmann equation

2016

View full text Add to dashboard Cite

It is well known that the roughness of the wall has an effect on microscale gas flows. This effect can be shown for large Knudsen numbers by using a numerical solution of the Boltzmann equation. However, when the wall is rough at a nanometric scale, it is necessary to use a very small mesh size which is much too expansive. An alternative approach is to incorporate the roughness effect in the scattering kernel of the boundary condition, such as the Maxwell-like kernel introduced by the authors in a previous paper. Here, we explain how this boundary condition can be implemented in a Discrete Velocity approximation of the Boltzmann equation. Moreover, the influence of the roughness is shown by computing the structure scattering pattern of mono-energetic beams of the incident gas molecules. The effect of the angle of incidence of these molecules, of their mass, and of the morphology of the wall is investigated and discussed in a simplified two-dimensional configuration. The effect of the azimuthal angle of the incident beams is shown for a three-dimensional configuration. Finally, the case of non-elastic scattering is considered. All these results suggest that our approach is a promising way to incorporate enough physics of gas-surface interaction, at a reasonable computing cost, to improve kinetic simulations of micro and nano-flows.

show abstract

Measurements of the relative momentum accommodation coefficient for different gases with a viscosity vacuum gauge

Cited by 31 publications

References 11 publications

Effects of gas species on pressure dependence of thermophoretic velocity

Effects of gas species on pressure dependence of thermophoretic velocity

Effect of gas adsorption on momentum accommodation coefficients in microgas flows using molecular dynamic simulations

Nanoscale roughness effect on Maxwell-like boundary conditions for the Boltzmann equation

Contact Info

Product

Resources

About