基于非结构/混合网格的高阶精度DG/FV混合方法研究进展

Recent development of high order DG/FV hybrid methods

  • 摘要: DG/FV混合方法因其具有紧致、易于推广获得高阶格式及相比同阶精度DG方法计算量、存储量小等优点,自提出以来已成功应用于一维、二维标量方程和Euler/N-S方程的求解。综述了DG/FV混合方法的研究进展,重点介绍了DG/FV混合方法的空间重构算法、针对RANS方程的求解方法、隐式时间离散格式、数值色散耗散及稳定性分析、计算量理论分析,并给出了系列粘性流算例的计算结果,包括用于验证混合方法数值精度的库埃特流,以及方腔流、亚声速剪切层、低速平板湍流、NACA0012翼型湍流绕流等。数值计算结果表明DG/FV混合方法达到了设计的精度阶,且相比同阶DG方法计算量减少约40%,而隐式方法能大幅提高定常流的收敛历程,较显式Runge-Kutta的收敛速度提高1~2个量级。

     

    Abstract: A concept of ‘static reconstruction’ and ‘dynamic reconstruction’ had been introduced for higher-order (third-order and higher) numerical methods in our previous work. Based on this concept, a class of DG/FV hybrid methods had been developed for the scalar equations and Euler/NS equations on triangular and Cartesian/triangular hybrid grids. In this paper, the recent progress of the DG/FV hybrid methods was presented. The basic idea of ‘hybrid reconstruction’, the procedure of solving NS equations with BR2 approach, and the implicit algorithm were reviewed briefly. And then the dissipative and dispersive property, as well as the stability, of the DG/FV hybrid schemes were analyzed. In order to show the high efficiency in the term of CPU time of the present DG/FV hybrid schemes, the computational costs were discussed and compared with the corresponding DG methods. The numerical accuracy was validated by some typical test cases of viscous flow, including the Couette flow, laminar flow in a square, compressible mixing layer problem, turbulent flows by RANS equations with S-A turbulent model over a flat plate and over NACA0012 airfoil. The accuracy study shows that the hybrid DG/FV method achieves the desired order of accuracy, and they can capture the flow structure accurately. Qualitative analysis and numerical applications demonstrate that they can reduce the CPU time greatly (up to 40%) comparing with the traditional DG method with the same order of accuracy. Meanwhile, the implicit algorithm can accelerate the convergence history obviously, one to two orders faster than the explicit RungeKutta method.

     

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