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基于弯曲网格的自适应间断有限元法研究
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摘要
为保证应用间断有限元方法(Discontinuous Galerkin Method,DGM)收敛稳定并且得到高精度的数值解,物面网格必须能够精确表达物面信息。同时,为了捕捉更关注的守恒量变化以及降低计算量,网格自适应也势在必行。本文设计了一套只有物面附近单元弯曲的方法,二维情况以6阶多项式表达物面,三维情况以3阶多项式表达。在此基础上,网格数值解多项式的高阶项贡献作为自适应的指示器进行网格的加密或放粗。二维情况以欧拉方程的圆柱绕流算例、激波捕捉算例、层流算例进行验证,三维情况以圆球物面构造和计算进行了验证。数值结果表明,采用文章提出的方法可以保证以尽量小的计算量得到高精度结果。
A high-order discontinuous method(DGM) is integrated with adaptive method to solve Euler equations on unstructured mesh.Contribution of the polynomial's highest-order terms is quantified in the form of artificial viscous coefficient.The coefficient is regarded as the indicator of h-adaptivity.Elements where the coefficients are greater than the upper limit are refined.Those where the coefficients are less than the lower limit are coarsened if they have been refined.A high-order geometric approximation of curved boundaries is adopted to ensure the convergence.Numerical results of test cases are consistent with corresponding experimental ones.High accurate numerical results can be obtained with the h-adaptive method at low expense.
引文
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