不定常差分方法中的二阶三层格式

 本文介绍一种求解三维理想可压流问题的二阶三层格式并给出它的稳定性证明。通过大量二维和三维问题的实际计算,表明此方法的优点是精度好,时间省,公式简单,程序量少,便于实际应用。文中对应用此法如何求解间断流场的问题,针对具体算例做了较详细的讨论。对不同外形在不同流动条件下,如何设计差分网格也做了分析。最后给出部分复杂外形的二维和三维计算结果。

SECOND-ORDER THREE-LEVEL SCHEME FOR TIME-DEPENDENT FINITE DIFFERENCE METHODS

A second-order three-level scheme for solving three-dimensional compressible ideal flow problems is presented, and its stability is proved. By carrying out a large number of practical calculations of two-dimensional and three-dimen- sional flow problems, it is shown that advantages of the scheme are good accuracy, reduced computer time, simplicity of formulas, reduced program-hours, and adaptability to practical application. How to apply the scheme to flowfields with discontinuities is discussed in detail in terms of some specific examples. How to construct the difference-nets for different configurations in different flow conditions is also analyzed. Finally, calculated results for some two-dimensional and three-dimensional complex configurations are given here. The results at fig. 8 are compared with the experiments of Ref. 4. It can be seen from the pressure distributions of Ref. 4 that there are really two subsonic regions in this kind of concave flowfields.