Transactions of the Korean Society of Mechanical Engineers B (대한기계학회논문집B)
- Volume 21 Issue 4
- /
- Pages.509-517
- /
- 1997
- /
- 1226-4881(pISSN)
- /
- 2288-5324(eISSN)
DOI QR Code
Analysis of rarefied compressible boundary layers in transition regime
천이영역의 희박기체 압축성 경계층 해석
- Choe, Seo-Won (Dept.of Mechanical Engineering, Hong-Ik University)
- 최서원 (홍익대학교 기계공학과)
- Published : 1997.04.01
Abstract
Results of flat plate compressible boundary layer calculation, based on discrete formulation of DSMC method, are presented in low Mach number and low Knudsen number range. The free stream is a uniform flow of pure nitrogen at various Mach numbers in low pressures (i.e. rarefied gas). Complete thermal accommodation and diffuse molecular reflections are used as the wall boundary condition, replacing unreal no-slip condition used in continuum calculations. In the discrete formulation of DSMC method, there is no need to use ad hoc assumptions on transport properties like viscosity and thermal conductivity, instead viscosity is calculated from values of other field variables (velocity and shear stress). Also the results are compared with existing self-similar continuum solutions. In all Mach number cases computed, velocity slip is most pronounced in regions near the leading edge where continuum formulation renders the solution singular. As the boundary layer develops further downstream, velocity slips asymptote to values that are between 10 to 20% of the magnitude of free stream velocity. When the free stream number density is reduced, so the gas more rarefied, the velocity slip increases as expected.
Keywords