简介:AmodificationofafiniteelementmethodofDouglasandRobertsforapproximatingthesolutionoftheequationsdescribingcompressiblemiscibledisplacementinaporousmediumisproposedandanalyzed.ThepressureistreatedbyaparabolicmixedfiniteelementmethodusingaRaviart-Thomasspaceofindexroveraquasiregularpartition,AnextensionoftheDarcyvelocityalongGausslinesisusedintheevaluationofthecoefficientsintheGalerkinprocedurefortheconcentration.Asimplecomputationalprocedureallowsthesuperconvergencepropertyofthefluidvelocitytoberetainedinourtotalalgorithm.
简介:Inthispaper,weareconcernedwithuniformsuperconvergenceofGalerkinmethodsforsingularlyperturbedreaction-diffusionproblemsbyusingtwoShishkin-typemeshes.Basedonanestimateoftheerrorbetweensplineinterpolationoftheexactsolutionanditsnumericalapproximation,aninterpolationpost-processingtechniqueisappliedtotheoriginalnumericalsolution.Thisresultsinapproximationexhibitsuperconvergencewhichisuniformintheweightedenergynorm.Numericalexamplesarepresentedtodemonstratetheeffectivenessoftheinterpolationpost-processingtechniqueandtoverifythetheoreticalresultsobtainedinthispaper.
简介:ConsiderL2-projectionuhofuton-degreefiniteelementspaceonone-dimensionaluniformgrids.TwodifferentclassesoftheorthogonalexpansioninanelementforconstructingasuperclosetofunctionuhareproposedandthensuperconvergenceforbothuhandDuhareproved.Whennisoddandnoboundaryconditionsareprescribed,thenuhisofsuperconvergenceatn+1orderGausspointsGn+1ineachelement.Whennisevenandfunctionvaluesontheboundaryareprescribed,thenuhisofsuperconvergenceatn+1orderpointsZn+1ineachelement.Iftheotherboundaryconditionsaregiven,thentheconclusionsarevalidinallelementsthatitsdistancefromtheboundary≥ch|lnh|.Theaboveconclusionsarealsovalid.forn-dergreerectangularelementQ1(n).
简介:Somesuperconvergenceresultsofgeneralizeddifferencesolutionforellipticboundaryvalueproblemaregiven.Itisshownthatoptimalpointsofthestressesforgeneralizeddifferencemethodarethesameasthatforfiniteelementmethod.
简介:ThepurposeofthispaperistostudythesuperconvergencepropertiesofRitz-Volterraprojection.ThroughconstructionanewtypeofGreenfunctionandmakinguseofitspropertiesandtheprincipleofduality,thepaperprovesthattheRitz-Volterraprojectiondefinedonr-1orderfiniteelementspacesofLagrangetypeinoneandtwospacevariablecasespossessesO(h2r~2)orderandO(h4+1|Inh|)ordernodalsuperconvergence,respectively,andthesametypeofsuperconver-genceresultsaredemonstratedforthesemidiscretefinitedementapproximatesolutionsofSoboleve-quations.
简介:集中和为在一个维的设定的一个不可思议地使不安的模型问题的不连续的Galerkin(DG)方法的超级集中性质被学习。由与DG答案的适当地选择的数字踪迹,存在和唯一使用DG方法,最佳的顺序L2错误界限,和2p+i顺序数字踪迹斧子的超级集中建立了。数字结果显示DG方法不甚至在一致网孔下面生产任何摆动。数字实验证明在一致网孔下面,获得数字踪迹的一致超级集中似乎不可能。不过,对所谓的Shishkin类型的实现的感谢协调,一致2p+1顺序超级集中数字地被观察。
简介:Inthispaper,weconsiderthelocaldiscontinuousGalerkinmethod(LDG)forsolv-ingsingularlyperturbedconvection-diffusionproblemsinone-andtwo-dimensionalset-tings.TheexistenceanduniquenessoftheLDGsolutionsareverified.Numericalex-perimentsdemonstratethatitseemsimpossibletoobtainuniformsuperconvergencefornumericalfluxesunderuniformmeshes.Thankstotheimplementationoftwo-typedif-ferentanisotropicmeshes,i.e.,theShishkinandanimprovedgrademeshes,theuniform2p+1-ordersuperconvergenceisobservednumericallyforbothone-dimensionalandtwo-dimensionalcases.
简介:Inthispaper,wepresenttheleast-squaresmixedfiniteelementmethodandinvestigatesuperconvergencephenomenaforthesecondorderellipticboundary-valueproblemsovertriangulations.OnthebasisoftheL2-projectionandsomemixedfiniteelementprojections,weobtainthesuperconvergenceresultofleast-squaresmixedfiniteelementsolutions.ThiserrorestimateindicatesanaccuracyofO(h3/2)ifthelowestorderRaviart-Thomaselementsareemployed.
简介:Wedeveloptheinterpolatedfiniteelementmethodtosolvesecond-orderhy-perbolicequations.Thestandardlinearfiniteelementsolutionisusedtogenerateanewsolutionbyquadraticinterpolationoveradjacentelements.Weprovethatthisinterpo-latedfiniteelementsolutionhassuperconvergence.Thismethodcaneasilybeappliedtogeneratingmoreaccurategradienteitherlocallyorglobally,dependingontheapplications.Thismethodisalsocompletelyvectorizableandparallelizabletotaketheadvantagesofmoderncomputerstructures.Severalnumericalexamplesarepresentedtoconfirmourtheoreticalanalysis.
简介:ThemainaimofthispaperistostudytheapproximationtoviscoelasticitytypeequationswithaCrouzeix-Raviarttypenonconformingfiniteelementontheanisotropicmeshes.Thesuperclosepropertyoftheexactsolutionandtheoptimalerrorestimateofitsderivativewithrespecttotimearederivedbyusingsomenoveltechniques.Moreover,employingapostprocessingtechnique,theglobalsuperconvergencepropertyforthediscretizationerrorofthepostprocesseddiscretesolutiontothesolutionitselfisstudied.