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(Heilongjiang University of Finance and Economics, Harbin 150025, China)
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ConstructionofallsingletravelingwavesolutionstoDullin-Gottwald-Holmequation
HOUMan-dan
(HeilongjiangUniversityofFinanceandEconomics,Harbin150025,China)
Bythecompletediscriminationsystemforpolynomialmethod,thispaperconstructedallsingletravelingwavesolutionstotheDullin-Gottwald-Holmequation.
completediscriminationsystemforpolynomialmethod;Dullin-Gottwald-Holmequation;travelingwavesolution
Itiswellknownthatthenonlinearpartialdifferentialequations(NLPDEs)arewidelyusedtodescribecomplexphenomenainvariousfieldsofsciences,particularlyinphysics.ExacttravelingwavesolutionofNLPDEsisoneofimportantinvestigationsinmathematicsphysics.Therearesomemethodsforgettingtheexactsolutionsoftheseequations,suchasthetransformedrationalfunctionmethod[1],themultipleexp-functionmethod[2-3],theextendedtanh-functionmethod[4],thesine-cosinemethod[5],thecompletediscriminationsystemforpolynomialmethod[6-9],andsoon.
TheDullin-Gottwald-Holm(DGH)equationwaspresentedbyDullinetal.[10],whichis
ut+c0ux+3uux-α2(uxxt+uuxxx+2uxuxx)+γuxxx=0
(1)
Recently,manypapersweredevotedtothestudyoftheDGHequation[11-17].GuoandLiuhaveobtainedexpressionsofcuspwavein[11],peakedwavesolutionsin[12],thenewboundedwavesolutions,compacton-likewavesolutionsandkink-likewavesolutionswithα2>0inreference[13].Dullinetal.haveshowedtheexistenceofthreetypesofboundedwavesforthecaseα2>0inreference[14].Inreference[15],someexplicitandimplicitexpressionsoffourtypesofboundedwaveshavebeenobtainedwithα2<0byTangandZhang.Inreference[16],anumberofexactsolutionshavebeengivenbytheExp-functionmethod.Newexactperiodicwavesolutionshavebeenobtainedbysemi-inversemethodandintegralbifurcationmethodinreference[17].Inreference[18],theorbitalstabilityofthetrainofNsolitarywaveshasbeenstudiedwiththedispersiveparameterγ=-c0α2.
However,weaimtoobtainallsingletravelingwavesolutionstotheDGHequation(1).Insection2,underfunctiontransformandthetravelingwavetransformation,weturnedEq. (1)intoanintegralequation.Insection3,byusingLiu’scompletediscriminationsystemforpolynomialmethod[6-9],weobtainedtheclassificationofallsingletravelingwavesolutionsofEq. (1).AllthesolutionshavebeenverifiedthattheyaresolutionsofEq. (1).
Underthetravelingwavetransformation,(x,t)=u(ζ),ζ=x-λt,wehave
(c0-λ)u′+3uu′-α2(-λu?+uu?)+λu?=0
(2)
whereλ(≠0)isthewavespeedand“′”isthederivativewithrespecttoζ.
IntegratingEq. (2)once,wehave
(3)
whereg0isanintegralconstant.
MultiplyingEq.(3)on2u′andintegratingitonceleadsto
(α2u-α2λ-γ)u′2=u3+(c0-λ)u2+g0u+g1
(4)
whereg1isanintegralconstant.
TheelementaryintegralformofEq.(4)is
±(ζ-ζ0)=
(5)
whereζ0isanintegralconstant.
Case1.α=0,γ≠0 .AccordingtoEq.(5),wehave
(6)
Takingthetransformation
(7)
wehave
f(w)=w3+b1w+b0
(8)
Denote
(9)
Δandb1makeupthecompletediscriminationsystemoff(w).
u=
(10)
andifa>w>b,then
u=
(11)
andifw>b>a,then
u=
(12)
Case2 Δ=0,b1=0,thenf(w)=w3,wehave
(13)
Case3 Δ>0,b1<0,thenf(w)=(w-a)(w-b)(w-c),wherea
u=
(14)
andifw>c,wehave
(15)
u=
(16)
Case5 α≠0
f(w)=w3+b1w+b0
(17)
Case6 Δ=0,b1=0,thenf(w)=w3.
Ifθ=1,whenw>max(0,σ)orw (18) (19) Case8 θ=1.Whenw>max(b,σ)orw<σ,thesolutionofEq. (1)is: ifa (20) andifmin(b,σ) (21) Case9 θ=-1.Whenmin(b,σ) ifa (22)