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arXiv 1505.01331math.NAcs.NA
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不可压缩流体一般边界条件的有限元公式

Finite element formulation of general boundary conditions for incompressible flows

University of Pau(波城大学)

Roland Becker, Daniela Capatina, Robert Luce, David Trujillo

AI总结:

本文研究了不可压缩流体问题中一般边界条件的有限元公式,通过Nitsche方法开发了一个适用于所有粘度参数值的离散加权弱形式,包括欧拉方程的极限情况,并通过数值实验验证了该方法的有效性。

摘要:

我们研究了不可压缩流体问题中一般边界条件的有限元公式。通过区分不可压缩流体方程中粘性部分和非粘性部分的贡献,我们使用Nitsche的方法开发了一个适用于所有粘度参数值的离散加权弱形式,包括欧拉方程的极限情况。为了控制离散动能,引入了额外的一致项。我们将极限情况视为一个(退化)的超双曲方程组,利用与可压缩流动相似的平衡谱分解方法分解通量雅可比矩阵。然后,根据Friedrichs系统的理论,将自然特征边界条件推广到所考虑的物理边界条件。展示了若干数值实验,包括标准粘性流动和无粘流动的基准测试。

英文摘要:

We study the finite element formulation of general boundary conditions for incompressible flow problems. Distinguishing between the contributions from the inviscid and viscid parts of the equations, we use Nitsche's method to develop a discrete weighted weak formulation valid for all values of the viscosity parameter, including the limit case of the Euler equations. In order to control the discrete kinetic energy, additional consistent terms are introduced. We treat the limit case as a (degenerate) system of hyperbolic equations, using a balanced spectral decomposition of the flux Jacobian matrix, in analogy with compressible flows. Then, following the theory of Friedrich's systems, the natural characteristic boundary condition is generalized to the considered physical boundary conditions. Several numerical experiments, including standard benchmarks for viscous flows as well as inviscid flows are presented.

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