Semiclassical Cross-Regime Rarefied Gas Flow Simulations Using Smooth Transition Zone
Date Issued
2014
Date
2014
Author(s)
Wei, Ting-Lin
Abstract
This study solves Semiclassical Boltzmann-BGK equation (also called Uehling – Uhlenbeck Boltzmann-Bhatnagar-Gross-Krook equation) with Maxwell-Boltzmann, Fermi-Dirac and Bose-Einstein statistics which allows us to simulate quantum gas flow problem. In this work, we also implement a buffering zone model which provides a smooth transition between a kinetic and a hydrodynamic domain. The idea is to use buffer zone splitting the velocity distribution function into two coupled equations by cut-off function. The solution will be recovered as the sum of the two coupled equations. We can easily determine to solve kinetic, hydrodynamic or coupled equations via cut function. Three types of cut-function, linear, cosine and hypertangent, are considered in this article. The idea of buffer zone can avoid issue of interface boundary condition between macroscopic and microscopic equation. For numerical parts, we use discrete ordinate method to remove the velocity space dependency of the velocity distribution function which renders Boltzmann equation in phase space to a set of hyperbolic conservation laws with source terms in physical space. High resolution schemes, Total Variation Diminishing (TVD) and Weighted Essentially Non-Oscillatory (WENO), are applied to physical space. Several semiclassical gas flow problems including 1-D shock tube problem, 2-D unsteady shock wave impinging upon a square cylinder and steady flow over a cylinder have been simulated to test the buffer zone treatment. Buffer zone performed well in each test problem. It can be implemented in Multi-scale coupling method successfully.
Subjects
半古典波茲曼BGK模型方程式
多尺度問題耦合法
平滑轉換區
尤拉極限
Type
thesis
File(s)![Thumbnail Image]()
Loading...
Name
ntu-103-R01543008-1.pdf
Size
23.54 KB
Format
Adobe PDF
Checksum
(MD5):e8c09bcf57c606f321a364bab176b2a3