6533b853fe1ef96bd12ad423

RESEARCH PRODUCT

Superconvergence phenomenon in the finite element method arising from averaging gradients

Pekka NeittaanmäkiMichal Křížek

subject

Piecewise linear functionComputational MathematicsRate of convergenceApplied MathematicsNumerical analysisMathematical analysisPiecewiseVector fieldSuperconvergenceConstant (mathematics)Finite element methodMathematics

description

We study a superconvergence phenomenon which can be obtained when solving a 2nd order elliptic problem by the usual linear elements. The averaged gradient is a piecewise linear continuous vector field, the value of which at any nodal point is an average of gradients of linear elements on triangles incident with this nodal point. The convergence rate of the averaged gradient to an exact gradient in theL 2-norm can locally be higher even by one than that of the original piecewise constant discrete gradient.

https://doi.org/10.1007/bf01379664