高速列车紊态外流场的数值模拟研究

高速列车是近地运行的细长、庞大物体，它的空气绕流问题有其特殊性。本文以不可压缩粘性流体的Navier-Stokes方程和k-ε两方程紊流模型为基础，采用有限元方法求解了高速列车三维紊态外流场。针对有限元法应用于流场计算时常出现的问题，采用分离式解法，非对称矩阵一维变带宽压缩存储及带宽极小化等方法，最大限度地降低计算存储量；并采用罚函数法，集中质量矩阵，缩减积分法，带参数迭代法以及引入松驰因子等技术，提出了一套用有限元法计算非线性问题的求解方法，提高了收敛速度的计算精度。计算方法和计算结果对列车空气动力学的深入研究有一定的帮助。

Numerical Simulation of Turbulent Flow FieldAround High-Speed Trains

The airflow surrounding a high-speed train, which is a slender huge body running near the ground, posesses its speciality. Based on Navier-Stokes equation and k- 2-equations turbulent model for incompressible viscous fluid, the 3D turbulent outside flow field around high-speed trains has been calculated by means of the finite element method. In this paper, some algorithms such as segregated solution method, compression store method of one-dimension variable bandwidth for unsymmetrical coefficient matrix and the minimization method of the matrix bandwidth have been presented or utilized to reduce the computer store as much as possible. Also, a set of methods for solving non-linear problems with the finite element method has been presented to raise the speed of convergence and the accuracy. In this set, penalty function method, assemblage mass matrix, reduced integration algorithm, Newton iteration method with parameters and relax factors are included. The calculation methods and results offered in the paper may be helpful to the deep study of vehicle aerodynamics.