Topic
Knudsen number
About: Knudsen number is a research topic. Over the lifetime, 5052 publications have been published within this topic receiving 104278 citations.
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TL;DR: In this paper, a numerical Monte Carlo algorithm has been developed and applied for the calculation of the ionic charging rate of small aerosol particles in the intermediate Knudsen regime.
47 citations
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TL;DR: In this article, the boundary conditions at the wall-uid interface in the Knudsen regime were investigated and the mean free path was comparable to the system size, where the wall interaction is attractive or repulsive.
Abstract: We show results of molecular dynamics studies of uid ows in the Knudsen regime in which the mean free path is comparable to the system size. We elucidate the boundary conditions at the wall{uid interface in such ows and nd scenarios envisioned by Maxwell. We also nd scenarios which do not agree with Maxwell’s hypothesis. We focus primarily on the case of repulsive walls and discuss similarities and dierences in behavior when the wall{uid interaction is attractive or repulsive. Striking many body eects are found on increasing the uid density as one interpolates between the dilute gas and the dense uid regimes. c 1999 Elsevier Science
47 citations
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TL;DR: In this article, a Poiseuille-flow problem in a cylindrical capillary in the whole range of Knudsen numbers with incomplete tangential momentum accommodation of molecules incident on the wall has been worked out.
Abstract: A Poiseuille-flow problem in a cylindrical capillary in the whole range of Knudsen numbers with incomplete tangential momentum accommodation of molecules incident on the wall has been worked out. The linear non-homogeneous integral equation for the macroscopic gas velocity flow has been solved by the Bubnov-Galerkin method. For a limited range of Knudsen numbers, generally known results have been obtained.An experimental investigation of the rare gases helium, neon and argon in the range of Knudsen numbers 103−10−3 has been made on packets consisting of 10 and 100 glass capillaries with molten walls. Comparison of theoretical and experimental data enables us to define both slip constants and tangential momentum accommodation coefficients. In the free-molecule flow regime the accommodation coefficients are 0·935, 0·929 and 0·975 for helium, neon and argon, respectively. In the viscous slip-flow regime these coefficients are equal to 0·895, 0·865 and 0·919, respectively. This difference in the tangential momentum accommodation coefficients is, most probably, due to the variable density of adsorbed molecules coating the capillary wall. Gas viscosity coefficients which coincide with those of Kestin within 0.5% have also been calculated. Argon was used as the calibrating gas.
47 citations
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TL;DR: In this article, a finite difference solution to the inviscid, compressible flow is used to explore the conditions for particle impaction in round sonic jet impactors, and the impaction parameter, Ψ_(50) defined in this manner does not appear to vary significantly with the jet pressure ratio, Mach number, or the particle Knudsen number.
46 citations
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06 Jun 2005TL;DR: The application of the Gaussian moment closure to micron-scale flows is considered in this paper, where a parallel upwind finite-volume scheme with adaptive mesh refinement using Roe and HLLE-type flux functions is described for solving the hyperbolic system of partial dierential equations arising from this closure.
Abstract: The application of the Gaussian moment closure to micron-scale flows is considered. The mathematical formulation of the closure is reviewed as well as an extension to allow for diatomic gases and treatment for solid wall boundaries. A parallel upwind finite-volume scheme with adaptive mesh refinement (AMR) using Roe and HLLE-type flux functions is described for solving the hyperbolic system of partial dierential equations arising from this closure. Comparisons are made between numerical solutions of the Gaussian model and analytical solutions for several test problems, including Couette, boundary layer and cylinder flow, over a range of Knudsen numbers. Agreement between analytical and numeric solutions for these problems are very encouraging.
46 citations