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An unstructured mesh Navier-Stokes solver employing a Maxwell slip boundary condition was developed. The present flow solver was applied to the simulation of flows around an axisymmetric hollow cylinder in a Mach 10.4 freestream, known as Calspan-UB Research Center (CUBRC) Run 14 case, and the velocity slip and the temperature jump on the cylinder surface were investigated. The effect of tangential momentum and thermal accommodation coefficients used in the Maxwell condition was also investigated by adjusting their values. The results show that the reverse flow region is developed on the body surface due to the interaction between the shock and the boundary layer. Also, the shock impingement makes pressure high. The flow properties on the surface agree well with the experimental data, and the velocity slip and the temperature jump vary consistently with the local Knudsen number change. The accommodation coefficients affect the slip phenomena and the size of the flow region. The slip phenomena become larger when both tangential momentum and thermal accommodation coefficients are decreased. However, the range of the reverse flow region decreases when the momentum accommodation coefficient is decreased. The characteristics of the momentum and thermal accommodation coefficients also are overlapped when they are altered together. [ABSTRACT FROM AUTHOR]

The lattice Boltzmann (LB) method has been used to simulate rarefied gas flows in micro-systems as an alternative tool, and shown its application possibility. For the rarefied gas flows, the surface roughness plays an important role for the slip phenomenon at the wall. If the wall surface is sufficiently rough, the reflection of the molecules will be diffuse and the tangential momentum accommodation coefficient (TMAC) is equal to unity. However, it has been known that the reflections are not always fully diffuse. In this study, rarefied gas flows are simulated in the slip and the transition flow regime including the effect of the TMAC. For the simulations, new non-fully diffuse wall boundary treatments of the LB method are proposed. The results of 2D and 3D simulations are in excellent agreement with the analytical solutions for the slip flow regime. The solutions of the linearized Boltzmann equation and DSMC for the transition flow regime are compared with those of high order LB method with present boundary conditions, and they are in excellent agreement. The tangential momentum accommodation coefficient effect is also investigated. [ABSTRACT FROM AUTHOR]