The critical accommodation coefficient for velocity inversion in rarefied cylindrical Couette flow in the slip and near free-molecular regimes

Stefan Stefanov, Robert W. Barber, David Emerson, Jason Reese

Research output: Chapter in Book/Report/Conference proceedingChapter

Abstract

This paper investigates velocity inversion in rarefied cylindrical Couette flow at the two extremes of the Knudsen number regime. For low Knudsen numbers, velocity inversion is independent of the accommodation coefficient of the inner cylinder and will only occur when the accommodation coefficient of the outer cylinder lies below a critical value. It is shown that this critical value depends upon the Knudsen number and the ratio of the outer and inner cylinders. In addition, velocity inversion is also investigated in the free-molecular and near free-molecular regimes. For the specific case of specular reflection at the outer cylinder, the present study has identified two distinct categories of molecules within the flow. The first category consists of particles that collide alternately with the inner and outer cylinders whilst the second consists of particles that never collide with the inner cylinder. It is shown that recognizing these different categories of particles is the key to understanding the velocity inversion process in the near free-molecular flow regime. Finally, for large but finite Knudsen numbers, our DSMC simulations demonstrate that velocity inversion does occur provided the accommodation coefficient of the outer cylinder is sufficiently small.
LanguageEnglish
Title of host publicationProceedings of the 25th International Symposium on Rarefied Gas Dynamics (RGD25)
Publication statusPublished - 2006

Fingerprint

accommodation coefficient
Couette flow
slip
inversions
Knudsen flow
free molecular flow
specular reflection

Keywords

  • couette flow
  • cylindrical
  • free-molecular
  • rarefication
  • velocity inversion

Cite this

Stefanov, S., Barber, R. W., Emerson, D., & Reese, J. (2006). The critical accommodation coefficient for velocity inversion in rarefied cylindrical Couette flow in the slip and near free-molecular regimes. In Proceedings of the 25th International Symposium on Rarefied Gas Dynamics (RGD25)
Stefanov, Stefan ; Barber, Robert W. ; Emerson, David ; Reese, Jason. / The critical accommodation coefficient for velocity inversion in rarefied cylindrical Couette flow in the slip and near free-molecular regimes. Proceedings of the 25th International Symposium on Rarefied Gas Dynamics (RGD25). 2006.
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abstract = "This paper investigates velocity inversion in rarefied cylindrical Couette flow at the two extremes of the Knudsen number regime. For low Knudsen numbers, velocity inversion is independent of the accommodation coefficient of the inner cylinder and will only occur when the accommodation coefficient of the outer cylinder lies below a critical value. It is shown that this critical value depends upon the Knudsen number and the ratio of the outer and inner cylinders. In addition, velocity inversion is also investigated in the free-molecular and near free-molecular regimes. For the specific case of specular reflection at the outer cylinder, the present study has identified two distinct categories of molecules within the flow. The first category consists of particles that collide alternately with the inner and outer cylinders whilst the second consists of particles that never collide with the inner cylinder. It is shown that recognizing these different categories of particles is the key to understanding the velocity inversion process in the near free-molecular flow regime. Finally, for large but finite Knudsen numbers, our DSMC simulations demonstrate that velocity inversion does occur provided the accommodation coefficient of the outer cylinder is sufficiently small.",
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Stefanov, S, Barber, RW, Emerson, D & Reese, J 2006, The critical accommodation coefficient for velocity inversion in rarefied cylindrical Couette flow in the slip and near free-molecular regimes. in Proceedings of the 25th International Symposium on Rarefied Gas Dynamics (RGD25).

The critical accommodation coefficient for velocity inversion in rarefied cylindrical Couette flow in the slip and near free-molecular regimes. / Stefanov, Stefan; Barber, Robert W.; Emerson, David; Reese, Jason.

Proceedings of the 25th International Symposium on Rarefied Gas Dynamics (RGD25). 2006.

Research output: Chapter in Book/Report/Conference proceedingChapter

TY - CHAP

T1 - The critical accommodation coefficient for velocity inversion in rarefied cylindrical Couette flow in the slip and near free-molecular regimes

AU - Stefanov, Stefan

AU - Barber, Robert W.

AU - Emerson, David

AU - Reese, Jason

PY - 2006

Y1 - 2006

N2 - This paper investigates velocity inversion in rarefied cylindrical Couette flow at the two extremes of the Knudsen number regime. For low Knudsen numbers, velocity inversion is independent of the accommodation coefficient of the inner cylinder and will only occur when the accommodation coefficient of the outer cylinder lies below a critical value. It is shown that this critical value depends upon the Knudsen number and the ratio of the outer and inner cylinders. In addition, velocity inversion is also investigated in the free-molecular and near free-molecular regimes. For the specific case of specular reflection at the outer cylinder, the present study has identified two distinct categories of molecules within the flow. The first category consists of particles that collide alternately with the inner and outer cylinders whilst the second consists of particles that never collide with the inner cylinder. It is shown that recognizing these different categories of particles is the key to understanding the velocity inversion process in the near free-molecular flow regime. Finally, for large but finite Knudsen numbers, our DSMC simulations demonstrate that velocity inversion does occur provided the accommodation coefficient of the outer cylinder is sufficiently small.

AB - This paper investigates velocity inversion in rarefied cylindrical Couette flow at the two extremes of the Knudsen number regime. For low Knudsen numbers, velocity inversion is independent of the accommodation coefficient of the inner cylinder and will only occur when the accommodation coefficient of the outer cylinder lies below a critical value. It is shown that this critical value depends upon the Knudsen number and the ratio of the outer and inner cylinders. In addition, velocity inversion is also investigated in the free-molecular and near free-molecular regimes. For the specific case of specular reflection at the outer cylinder, the present study has identified two distinct categories of molecules within the flow. The first category consists of particles that collide alternately with the inner and outer cylinders whilst the second consists of particles that never collide with the inner cylinder. It is shown that recognizing these different categories of particles is the key to understanding the velocity inversion process in the near free-molecular flow regime. Finally, for large but finite Knudsen numbers, our DSMC simulations demonstrate that velocity inversion does occur provided the accommodation coefficient of the outer cylinder is sufficiently small.

KW - couette flow

KW - cylindrical

KW - free-molecular

KW - rarefication

KW - velocity inversion

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UR - http://onlinereg.ru/40/first.pdf

M3 - Chapter

BT - Proceedings of the 25th International Symposium on Rarefied Gas Dynamics (RGD25)

ER -

Stefanov S, Barber RW, Emerson D, Reese J. The critical accommodation coefficient for velocity inversion in rarefied cylindrical Couette flow in the slip and near free-molecular regimes. In Proceedings of the 25th International Symposium on Rarefied Gas Dynamics (RGD25). 2006