简介:Abstract.OgrobjectinthisartlcleistodescribetbeGalerklnschemeandnonlin-eaxGalerkinschemefortheapproximationofnonlinearevolutionequations,andtostudythestabilityoftheseschemes.SpatialdiscretizatloncanbepedormedbyeitherGalerklnspectralmethodornonlinearGalerldnspectralmethod;timediscretizatlortisdonehyEulersin.heinewklchisexplicitorimplicitinthenonlinearterms.Accordingtothestabilityanalysisoftheaboveschemes,thestabilityofnonllneexGalerklnmethodisbetterthanthatofGalexklnmethod.
简介:TheGalerkinandleast-squaresmethodsaretwoclassesofthemostpopularKrylovsubspacemethOdsforsolvinglargelinearsystemsofequations.Unfortunately,boththemethodsmaysufferfromseriousbreakdownsofthesametype:InabreakdownsituationtheGalerkinmethodisunabletocalculateanapproximatesolution,whiletheleast-squaresmethod,althoughdoesnotreallybreakdown,isunsucessfulinreducingthenormofitsresidual.Inthispaperwefrstestablishaunifiedtheoremwhichgivesarelationshipbetweenbreakdownsinthetwometh-ods.Wefurtherillustratetheoreticallyandexperimentallythatifthecoefficientmatrixofalienarsystemisofhighdefectivenesswiththeassociatedeigenvalueslessthan1,thentherestart-edGalerkinandleast-squaresmethodswillbeingreatrisksofcompletebreakdowns.Itappearsthatourfindingsmayhelptounderstandphenomenaobservedpracticallyandtoderivetreat-mentsforbreakdownsofthistype.
简介:Inthispaper,theminimaldissipationlocaldiscontinuousGalerkinmethodisstudiedtosolvetheellipticinterfaceproblemsintwo-dimensionaldomains.Theinterfacemaybearbitrarysmoothcurves.ItisshownthattheerrorestimatesinL2-normforthesolutionandthefluxareO(h2|logh|)andO(h|logh|^l/2),respectively.Innumericalexperiments,thesuccessivesubstitutioniterativemethodsareusedtosolvetheLDGschemes.Numericalresultsverifytheefficiencvandaccuracvofthemethod.
简介:ItisprovedinthispaperthattheapproximatesolutionofthediscontinuousGalerkinmethoddoesconvergeeventheexactsolutionofthefirstorderhyperbolicequationisdiscontinuous.
简介:几个Galerkin-Petrov方法,包括的多项式搭配和分析元素的集中在Dirichlet空间的Toeplitz操作员的搭配方法,被建立。特别地,如果基础和测试功能拥有某些圆形的对称,如此的方法收敛,这被显示出。给词调音:GalerkinPetrov方法;多项式搭配;分析元素搭配;Toeplitz操作员;Dirichlet空间
简介:Weperformanalysisforafiniteelementsmethodappliedtothesingularself-adjointproblem.Thismethodusescontinuouspiecewisepolynomialspacesforthetrialandthetestspaces.WefitthetrialpolynomialspacebypiecewiseexponentialsandweapplysoexponentiallyfittedGalerkinmethodtosingularself-adjomtproblembyapproximatingdrivingtermsbyLagrangepiecewisepolynomials,linear,quadraticandcubic.Wtmeasuretheerroeinmaxnorm.Weshowthatmethodisoptimalofthefirstorderintheerrorestimate,WealsogivenumericalresultsfortheGalerkinapproximation.
简介:NonlinearGalerkinmethodsarenewschemesforintegratingdissipativesystems:Inthepresentpaper,weobtaintheestimatestotherateofconvergenceofsuchmethodsforKuramoto-Sivashinskyequations.Inparticular,byanillustrativeexample,weshowthatnonlinearGalerkinmethodsconvergefasterthantheusualGalerkinmethod.
简介:Inthispaper,aunifiedmodelfortime-dependentMaxwellequationsindispersivemediaisconsidered.Thespace-timeDGmethoddevelopedin[29]isappliedtosolvetheunderlyingproblem.UnconditionalL2-stabilityanderrorestimateoforderOτr+1+hk+1/2areobtainedwhenpolynomialsofdegreeatmostrandkareusedforthetemporaldiscretizationandspatialdiscretizationrespectively.2-Dand3-Dnumericalexamplesaregiventovalidatethetheoreticalresults.Moreover,numericalresultsshowanultra-convergenceoforder2r+1intemporalvariablet.
简介:Inthispaper,weuseDaubechiesscalingfunctionsastestfunctionsfortheGalerkinmethod,anddiscussWavelet-GalerkinsolutionsfortheHamilton-Jacobiequations.ItcanbeprovedthattheschemesareTVDschemes.NumericaltestsindicatethattheschemesaresuitablefortheHamilton-Jacobiequations.Furthermore,theyhavehigh-orderaccuracyinsmoothregionsandgoodresolutionofsingularities.
简介:AbstractAsystemofquasilinearcoupledequationswhicharisefromsimulationofcontaminationofgeologicnulearwasteinporousmediaisstudied.We’lldiscussGalerkinmethodforthemodelofcompressibleflowwithmoleculardiffusionanddispersion.Somenewtechniquesareintrocuedtoerroranalysis.Onlyonedimensionalcaseisconsidered.TheoptimalerrorestimateinbothL~2andH~1isproved.Acontributionofthispaperishowthedispersiontermcanbehandled,
简介:Inthispaper,a-posteriorierrorestimatorsareproposedfortheLegendrespectralGalerkinmethodfortwo-pointboundaryvalueproblems.ThekeyideaistopostprocesstheGalerkinapproximation,andtheanalysisshowsthatthepostprocessimprovestheorderofconvergence.Consequently,weobtainasymptoticallyexactaposteriorierrorestimatorsbasedonthepostprocessingresults.Numericalexamplesareincludedtoillustratethetheoreticalanalysis.
简介:Analternating-directionimplicit(ADI)Galerkinnuthodwithmovingfiniteelementspacesisformulatedforaclassofsecond-orderhyperbolicequationsintwospacevariables.AprioriH1-errorestimateisderived.
简介:AnA.D.I.Galerkinschemeforthree-dimensionalnonlinearparabolicintegro-differen-tialequationisstudied.Byusingalternating-direction,thethree-dimensionalproblemisreducedtoafamilyofsinglespacevariableproblems,thecalculationissimplified;byusingalocalapproxima-tionofthecoefficientsbasedonpatchesoffiniteelements,thecoefficientmatrixisupdatedateachtimestep;byusingRitz-Volterraprojection,integrationbypartandothertechniques,theinfluencecomingfromtheintegraltermistreated;byusinginductivehypothesisreasoning,thedifficultycomingfromthenonlinearityistreated.ForbothGalerkinandA.D.I.Galerkinschemesthecon-vergencepropertiesarerigorouslydemonstrated,theoptimalH~1-normandL~2-normestimatesareobtained.
简介:Ahigh-orderleap-frogbasednon-dissipativediscontinuousGalerkintime-domainmethodforsolvingMaxwell'sequationsisintroducedandanalyzed.Theproposedmethodcombinesacenteredapproximationfortheevaluationoffluxesattheinterfacebetweenneighboringelements,withaNth-orderleap-frogtimescheme.Moreover,theinterpolationdegreeisdefinedattheelementlevelandthemeshisrefinedlocallyinanon-conformingwayresultinginarbitrarylevelhangingnodes.ThemethodisprovedtobestableundersomeCFL-likeconditiononthetimestep.Theconvergenceofthesemi-discreteapproximationtoMaxwell'sequationsisestablishedrigorouslyandboundsontheglobaldivergenceerrorareprovided.Numericalexperimentswithhigh-orderelementsshowthepotentialofthemethod.