简介:EQrot1nonconformingfiniteelementapproximationtoaclassofnonlineardualphaselaggingheatconductionequationsisdiscussedforsemi-discreteandfully-discreteschemes.Byuseofaspecialproperty,thatis,theconsistencyerrorofthiselementisoforderO(h2)oneorderhigherthanitsinterpolationerrorO(h),thesupercloseresultsoforderO(h2)inbrokenH1-normareobtained.Atthesametime,theglobalsuperconvergenceinbrokenH1-normisdeducedbyinterpolationpostprocessingtechnique.Moreover,theextrapolationresultwithorderO(h4)isderivedbyconstructinganewinterpolationpostprocessingoperatorandextrapolationschemebasedontheknownasymptoticexpansionformulasofEQrot1element.Finally,optimalerrorestimateisgainedforaproposedfully-discreteschemebydifferentapproachesfromthepreviousliterature.