A nonconforming P3 and discontinuous P2 mixed finite element on tetrahedral grids

Fuente: arXiv
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Main Authors: Xu, Xuejun, Zhang, Shangyou
Format: Preprint
Published: 2024
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author Xu, Xuejun
Zhang, Shangyou
author_facet Xu, Xuejun
Zhang, Shangyou
contents A nonconforming $P_3$ finite element is constructed by enriching the conforming $P_3$ finite element space with three $P_3$ nonconforming bubbles and six additional $P_4$ nonconforming bubbles, on each tetrahedron. Here the divergence of the $P_4$ bubble is not a $P_3$ polynomial, but a $P_2$ polynomial. This nonconforming $P_3$ finite element, combined with the discontinuous $P_2$ finite element, is inf-sup stable for solving the Stokes equations on general tetrahedral grids. Consequently such a mixed finite element method produces quasi-optimal solutions for solving the stationary Stokes equations. With these special $P_4$ bubbles, the discrete velocity remains locally pointwise divergence-free. Numerical tests confirm the theory.
format Preprint
id arxiv_https___arxiv_org_abs_2408_10226
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle A nonconforming P3 and discontinuous P2 mixed finite element on tetrahedral grids
Xu, Xuejun
Zhang, Shangyou
Numerical Analysis
A nonconforming $P_3$ finite element is constructed by enriching the conforming $P_3$ finite element space with three $P_3$ nonconforming bubbles and six additional $P_4$ nonconforming bubbles, on each tetrahedron. Here the divergence of the $P_4$ bubble is not a $P_3$ polynomial, but a $P_2$ polynomial. This nonconforming $P_3$ finite element, combined with the discontinuous $P_2$ finite element, is inf-sup stable for solving the Stokes equations on general tetrahedral grids. Consequently such a mixed finite element method produces quasi-optimal solutions for solving the stationary Stokes equations. With these special $P_4$ bubbles, the discrete velocity remains locally pointwise divergence-free. Numerical tests confirm the theory.
title A nonconforming P3 and discontinuous P2 mixed finite element on tetrahedral grids
topic Numerical Analysis
url https://arxiv.org/abs/2408.10226