差分格式的优化组合

用偏微分方程组解实际的三维紊流流动问题时,如何选择各方程中对流项和扩散项的差分格式将对计算的稳定性、准确性与经济性影响很大.对一个实际的流动问题,计算机模拟验证了迎风差分、中心差分、混和格式、PLDS(Power Law Differencing Scheme)、QUICK(二次迎风插值)和OPTIMAL(Oscillation Preventing Technical algorithm based on the second-order Interpolation Method for Advection Linked convection)的各种组合对计算的稳定性、准确性与经济性的影响.对中心差分应用在雷诺时均方程中出现的数值解的振荡问题提出了在局部网格使用迎风差分的具体对策.对QUICK应用在κ,ε输运方程上出现的数值解的发散问题提出了QUICK和迎风差分格式交替使用的具体方法.

Optimum Association of Difference Schemes

The selection of the finite difference schemes for the convective and diffusion terms of the governing equations of fluid flow has great influence on the computational stability, accuracy and time. In this paper, various combinations of difference schemes, including Central difference, Up-wind, Hybrid, PLDS, QUICK and OPTIMAL, are used to compute the turbulent flow in 3-D room for comparing the stability, accuracy and computational time. A new conception thus obtained reflects in the following aspects. The local use of Up-wind method can eliminate the oscillation of the solution when Reynolds equation is applied in Central difference. Besides, the combination of QUICK and Up-wind method is also proposed to solve the problem that the solution of κ,ε equations diverges when QUICK method is used.