Navier-Stokes型变分不等式的两水平梯度–散度稳定化方法

Two-Level Gradient-Divergence Stabilization Method for Navier-Stokes Type Variational Inequalities

  • 摘要: 本文提出一种梯度–散度(grad-div)稳定化的两水平有限元方法。该方法采用分层策略:首先在一粗网格上求解含梯度-散度稳定项的非线性Navier-Stokes型变分不等式问题,得到一个粗网格解;然后在一细网格上以粗网格解线性化非线性的对流项,求解一个Oseen、Stokes或Newton线性化问题得到最终解,并利用梯度–散度稳定项抑制压力对速度的影响。从理论上估计了该数值方法所得近似解的误差界,并通过数值试验验证了理论结果的正确性和数值方法的有效性。数值结果表明,与标准的两水平有限元方法相比,该方法显著提升了速度近似解的精度。

     

    Abstract: This paper proposes a gradient–divergence (grad–div) stabilized two-level finite element method. The method adopts a hierarchical strategy: first, a nonlinear Navier-Stokes-type variational inequality problem incorporating a grad–div stabilization term is solved on a coarse grid to yield a coarse-grid solution; subsequently, the nonlinear convective term is linearized via the coarse-grid solution on a fine grid, and a linearized problem (of Oseen, Stokes, or Newton type) is solved to derive the final solution. The grad–div stabilization term serves to suppress pressure's influence on velocity. Theoretical error bounds for the approximate solutions of this numerical method are established, and numerical experiments validate the correctness of the theoretical results as well as the method's effectiveness. Numerical findings demonstrate that, in comparison with the standard two-level finite element method, the proposed method achieves a significant enhancement in the accuracy of velocity approximations.

     

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