We devise variants of classical nonconforming methods for symmetric elliptic problems. These variants differ from the original ones only by transforming discrete test functions into conforming functions before applying the load functional. We derive and discuss conditions on these transformations implying that the ensuing method is quasi-optimal and that its quasi-optimality constant coincides with its stability constant. As applications, we consider the approximation of the Poisson problem with Crouzeix--Raviart elements and higher order counterparts and the approximation of the biharmonic problem with Morley elements. In each case, we construct a computationally feasible transformation and obtain a quasi-optimal method with respect to the piecewise energy norm on a shape regular mesh.
|Titolo:||Quasi-optimal nonconforming methods for symmetric elliptic problems. II-Overconsistency and classical nonconforming elements|
ZANOTTI, PIETRO (Corresponding)
|Parole Chiave:||quasi-optimality; nonconforming elements; Crouzeix--Raviart elements; Morley element|
|Settore Scientifico Disciplinare:||Settore MAT/08 - Analisi Numerica|
|Data di pubblicazione:||2019|
|Digital Object Identifier (DOI):||10.1137/17M1151651|
|Appare nelle tipologie:||01 - Articolo su periodico|