时间依赖边界条件在亚声速自由射流数值模拟中的应用

对亚声速自由射流进行数值模拟时，无法预先给定远场边界和无反射入流边界上的速度值。以往采用的黎曼不变量在自由边界上给定无反射条件的处理方法，只给出了这些边界法线方向上的一维特征关系。时间依赖边界条件是一种高精度的边界处理方法，可以很方便地处理计算中遇到的各种边界，广泛地应用于DNS中。我们将这种边界条件用于定常流动的计算中，计算了出口马赫数为0．4和0．7的轴对称自由射流，获得了与实验结果吻合的数值模拟结果。

Numerical simulation of subsonic free jet with time-dependent boundary conditions

There are several kinds of boundaries such as open boundaries in the numerical simulation of subsonic free jet problems. It is difficult to impose boundary conditions at the open boundaries because the physical variables such as velocities can not be specified entirely. A common method is imposing nonreflecting boundary conditions with the help of Riemann invariables. But the physical problem is simplified as a 1 D problem at the boundary in this method. Time dependent boundary conditions (TDBC), which are accurate boundary conditions and can be used to treat kinds of boundaries in computations easily, are widely used in DNS. We use the time dependent boundary conditions to simulate the steady free jet problems. The free jet problems with Ma=0.4 and Ma=0.7 are simulated and the results are coincided with the experimental data well.