Diffuse scattering of gas molecules from conical surface roughness

Sawada, Ta-i; Horie, B Yukari; Sugiyama, Wataru

doi:10.1016/0042-207x(96)00069-3

Cited by 12 publications

(10 citation statements)

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“…Note again, the reflection point is assumed to be the same as the initial approach point, therefore, the actual value of h is not important (for example, h = 1m can be used). In this algorithm, there are no uncertainties associated with the cut-off for very long traveling distances such as those in [3]. It can also be easily implemented in DSMC.…”

Section: Conical Model Of Surface Roughness For Particle Approachesmentioning

confidence: 99%

“…The description of rough surfaces has been approached before, both using simplified models such as cone models [3,4] as well as more sophisticated models such as fractals models [5,6]. The conical roughness model [4] where the surface is represented by a number of virtual cones has been applied to model the flow conductance in channels with the direct simulation Monte Carlo method, and the results were compared with available experimental data.…”

Section: Introductionmentioning

confidence: 99%

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Surface Roughness Effects in Low Reynolds Number Channel Flows

Gimelsheim¹,

Duncan²,

Lilly³

et al. 2006

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Public reporting burden for this collection of information is estimated to average 1 hour per response, including the time for reviewing instructions, searching existing data sources, gathering and maintaining the data needed, and completing and reviewing this collection of information. Send comments regarding this burden estimate or any other aspect of this collection of information, including suggestions for reducing this burden to Department of Defense, Washington Headquarters Services, Directorate for Information 14. ABSTRACT Rarefied helium and nitrogen flow expanding into vacuum through 150µm high and 1.5 cm long channels is studied experimentally and numerically with the DSMC method. Different types of channel walls are examined, both polished and rough with well characterized roughness shaped as triangles and rectangles. The pressure varies from 200 to 13,000 Pa, with the gas mean free path being both much larger and much smaller than the roughness size of about 20µm. A conical surface roughness model applicable for the DSMC method is proposed. An expression relating this model to the Cercignani-Lampis scattering model is derived. Good agreement between the numerical and experimental results is observed for the rough walled channel. Abstract. Rarefied helium and nitrogen flow expanding into vacuum through 150µm high and 1.5 cm long channels is studied experimentally and numerically with the DSMC method. Different types of channel walls are examined, both polished and rough with well characterized roughness shaped as triangles and rectangles. The pressure varies from 200 to 13,000 Pa, with the gas mean free path being both much larger and much smaller than the roughness size of about 20µm. A conical surface roughness model applicable for the DSMC method is proposed. An expression relating this model to the Cercignani-Lampis scattering model is derived. Good agreement between the numerical and experimental results is observed for the rough walled channel.

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Section: Conical Model Of Surface Roughness For Particle Approachesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Surface Roughness Effects in Low Reynolds Number Channel Flows

Gimelsheim¹,

Duncan²,

Lilly³

et al. 2006

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“…A number of statistical models of the wall roughness such as randomly distributed conical surfaces, periodically corrugated channel surface etc. was proposed in [6,2,7,8,9]. Other example of the statistical model is an application of porous media model for rough microchannels [10].…”

Section: Introductionmentioning

confidence: 99%

Statistical Simulation of Gas Flows through Short Rough Microchannels

Markelov¹,

Stefanov²

2011

AIP Conference Proceedings

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Rarefied gas flow though the rough microchannel is modeled using the direct simulation Monte Carlo method (DSMC). Deterministic and statistical methods of wall roughness deception have been applied. The well-known DSMC-based software, SMILE, allows one to model a flow through the channel with an arbitrary shape, here series of triangular obstacles has been modeled. A statistical approach is based on porous layer model of dusty gas and the model has been implemented in SMILE. Results obtained with two methods are compared and channel performance is presented for different pressure ratio and size of obstacles.

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“…This function depends on many characteristics of the gas and the surface, and also on thermodynamic parameters of the system as a whole. One factor exerting a significant effect on energy and momentum transfer in the gas-solid system is physical inhomogeneity (roughness) of the surface.Because of the lack of information about the surface structure and its role in gas-solid interaction, approaches with the use of absolutely smooth surfaces or extremely simple roughness models are usually used [2]. The influence of the surface structure on the free-molecular gas flow in cylindrical channels was studied in experiments [3,4].…”

mentioning

confidence: 99%

“…Because of the lack of information about the surface structure and its role in gas-solid interaction, approaches with the use of absolutely smooth surfaces or extremely simple roughness models are usually used [2]. The influence of the surface structure on the free-molecular gas flow in cylindrical channels was studied in experiments [3,4].…”

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confidence: 99%

Numerical simulations of gas-dynamic conductivity of microchannels with allowance for their surface structure

Ukhov¹,

Porodnov²,

Borisov

2009

J Appl Mech Tech Phy

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The effect of the microchannel surface structure on the free-molecular gas flow is studied by the testparticle method. Simulations are performed for channels whose surface either is obtained by means of statistical modeling or is reconstructed from the data of atomic-force microscopy of real surfaces. Dependences of monochromatic molecular beam scattering on the angle of incidence and the average height of microscopic roughness elements on the surface are considered. It is demonstrated that the method developed allows one to obtain the distribution function for particles reflected from a rough surface and to use it in the boundary conditions in problems of rarefied gas dynamics.Key words: rarefied gas flow in microchannels, Monte Carlo test-particle method, gas-surface interaction, scattering indicatrices, atomic-force microscopy.Introduction. In solving gas-dynamic problems associated with re-entry of flying vehicles into the upper atmospheric layers or with gas flows in microscale or nanoscale devices, one should take into account the parameters characterizing the structure and chemical composition of the surface. Numerous experimental studies show that the surface structure, its temperature, and other factors exert a significant effect on scattering of rarefied gas molecules and, as a consequence, on the gas-dynamic drag and heat transfer in the gas-solid system [1].One important component of the model of gas dynamics in external and internal flows are the boundary conditions for the Boltzmann equation, which imply that the distribution function of gas molecules reflected from the surface is available in an analytical form. This function depends on many characteristics of the gas and the surface, and also on thermodynamic parameters of the system as a whole. One factor exerting a significant effect on energy and momentum transfer in the gas-solid system is physical inhomogeneity (roughness) of the surface.Because of the lack of information about the surface structure and its role in gas-solid interaction, approaches with the use of absolutely smooth surfaces or extremely simple roughness models are usually used [2]. The influence of the surface structure on the free-molecular gas flow in cylindrical channels was studied in experiments [3,4].The development of methods of computer modeling and the use of new experimental technologies, in particular, scanning probe microscopy, allow certain progress to be achieved in numerical simulations of gas scattering on rough surfaces and in the description of rarefied gas flows in channels with the surface structure corresponding to conditions of physical experiments [5][6][7].The use of atomic force microscopy allows one to obtain high-resolution three-dimensional topograms. The thus-obtained digitized surface is an array whose elements contain the coordinates of each point of the surface of the examined sample. In the present work, we used the coordinates of 160 thousand points on the surface of a 20 × 20 μm silicon single crystal. In the course of studying the specified...

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Diffuse scattering of gas molecules from conical surface roughness

Cited by 12 publications

References 1 publication

Surface Roughness Effects in Low Reynolds Number Channel Flows

Surface Roughness Effects in Low Reynolds Number Channel Flows

Statistical Simulation of Gas Flows through Short Rough Microchannels

Numerical simulations of gas-dynamic conductivity of microchannels with allowance for their surface structure

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