Transport Properties of Small Spherical Particles

Wang, Shuangfeng

doi:10.1111/j.1749-6632.2008.04319.x

Cited by 12 publications

(12 citation statements)

References 25 publications

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“…A previous study [35] indicates that for spherical particles below 10 nm in particle diameter the momentum accommodation ϕ decreases from approximately unity to zero as the particle size is decreased. That is, the collision becomes specular as the particle size approaches the molecular size.…”

Section: Reduced Collision Integrals and Electric Mobility Of Cntsmentioning

confidence: 89%

“…For this reason, we introduced a momentum accommodation function ϕ [34,35] ( 0 ≤ ϕ ≤ 1) and demonstrated the variation of ϕ with respect to particle size for several particle materials [35]. Following the earlier approach [32], we write the drag-force expression for a cylinder in a similar manner:…”

Section: Scattering Modelmentioning

confidence: 99%

“…The problem arises from an increased effect of potential energy of gas-phase interaction as the particle approaches the molecular size [35].…”

Section: Reduced Collision Integrals and Electric Mobility Of Cntsmentioning

confidence: 99%

“…It has been identified earlier that the origin of diffuse scattering is molecular adsorption/desorption on particle surface [34,35], which is applicable to NSBs also. Drag force expressions are obtained for cylinders that undergo Brownian rotation and for those that align with the drift velocity.…”

Section: Introductionmentioning

confidence: 96%

“…For that size range, further complication many stem from changes in the dominant mode of molecular scattering. As the particle size is decreased to a few nanometers the collision evolves from diffuse to specular scattering [34,35]. In general, diffuse scattering yields a drag larger than specular scattering (cf , FIG 1).…”

Section: Introductionmentioning

confidence: 99%

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Drag force and transport property of a small cylinder in free molecule flow: A gas-kinetic theory analysis

Liu

Wang

2016

Phys. Rev. E

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Analytical expressions are derived for aerodynamic drag force on small cylinders in the free molecule flow using the gas kinetic theory. The derivation considers the effect of intermolecular interactions between the cylinder and gas media. Two limiting collision models, specular and diffuse scattering, are investigated in two limiting cylinder orientations with respect to the drift velocity. The earlier solution of Dahneke (B. E. Dahneke, Journal of Aerosol Science 4, 147, 1973) is shown to be a special case of the current expressions in the rigid-body limit of collision.Drag force expressions are obtained for cylinders that undergo Brownian rotation and for those that align with the drift velocity. The validity of the theoretical expressions is tested against experimental mobility data available for carbon nanotubes.

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Section: Reduced Collision Integrals and Electric Mobility Of Cntsmentioning

confidence: 89%

Section: Scattering Modelmentioning

confidence: 99%

“…The problem arises from an increased effect of potential energy of gas-phase interaction as the particle approaches the molecular size [35].…”

Section: Reduced Collision Integrals and Electric Mobility Of Cntsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 96%

Section: Introductionmentioning

confidence: 99%

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Drag force and transport property of a small cylinder in free molecule flow: A gas-kinetic theory analysis

Liu

Wang

2016

Phys. Rev. E

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Scattering Kernel Kinetic Approach of Small Particles Transport in a Free Molecular Regime in Gaseous Media

Pollito

Silva

2020

Braz J Phys

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We investigated through the scattering kernel kinetic concept the transport of small particles in gaseous media in a free molecular regime. The scattering kernel is generally used to provide gas-surface interaction boundary conditions for Boltzmann kinetic equation in flow problems (Maxwell, Phil. Trans. R. Soc. 170, 231, 1879; Sharipov, 2001). We developed a general expression for the transport force explicitly in terms of the scattering kernel and of gas molecule velocity distribution function. From the general expression, first, we could use the first-order Chapman-Enskog solution for the distribution function of gas molecules f (r, v, t) which shows three types of transportation mechanisms, or forces, such that F = F D +F T +F S. Where F D is the drag force on the particle due to its relative motion in the gas, F T is the thermophoretic force due to a gradient of temperature in the gas, and F S is due to shear forces on the particle. Second, it is possible to use any of the several scattering kernel models published in the literature. The traditional simple reflection kernels, specular, diffuse, and Maxwell, which comprises particular cases of the generalized force, are limited and do not fully describe the real reflection mode of molecule-particle interaction. So, we used the general (Struchtrup, Phys. Fluids. 25, 112001, 2013) reflection kernel model to study the drag force on small particles. The results were compared with available experimental data. We concluded that it is necessary to explicitly include impact velocity and particle surface rugosity effects which are predicted by the Struchtrup reflection kernel thermal activation model of molecule-particle interaction. Keywords Scattering kernels • Drag force • Small particles • Diffusion 1 Introduction Richard Feynman in December 1959 in his now classic premonitory talk, "There's Plenty of Room at the Bottom-An Invitation to Enter a New Field of Physics," opened the road to nanotechnology. Today we see nanoparticles technology successfully used in a wide range of areas: nanosensors, environmental applications, aerospace engineering, medicine, biotechnology, semiconductors, atmospheric science, material processing, etc. In all these areas, some fundamental particle transport properties such as drag force, diffusion coefficients, electric mobility, thermodiffusion,

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