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1,2,1,1(11,230026;21,212013):,k2Boussinesq,,,Fr2pGr/Re2,:;;:P732:A:100126791(2007)0620846207:2006209225;:200721215:(2004AA601065):(1980-),,,,,E2mail:cyjiang@mail1ustc1edu1cn,[15],,,,[6,7][3,4,811]1945Anderson,[12],[4,5,11,13]1997Krebs[3],[14]Zhou,[15]Wells1,1Fig11Clarifierandgridinthesimulation,[5]2000,Taebi2Harandy012[11],[16][3,4,15,17],ZhouCFD[13]Wells,,[5]Alonso[18],,186200711ADVANCESINWATERSCIENCEVol118,No16Nov.,2007,Boussinesq,Wells[5],11111,,,,,:11111:55t(qq)+¨(qqq)=mpq-mqp+Sq(1)qq;qq;qq;mpqpq;mqpqp;Sq,011112:55t(qqq)+¨(qqqq)=-q¨p+¨=q+qqg+Rpq(2)=q=qq(¨q+¨Tq)+qq-23q¨qI=(3);g;Rpq;qq;qq(2)Rpq,,Rpq=-RqpRqq=0,Schiller2naumann[19]11113:55t(qqhq)+¨(qquqhq)=-q5pq5t+=q:¨qq+Sq+Qpq(4)hqq;qq;Sq;QpqpqQpq=-Qqp,Qqq=0,ranz2marshall[20,21]Boussinesq,Boussinesq,(qqg):(-0)g=-T0g(5);0;T;;g(),(T-T0)1,112,,,,J:J=Jsn+Jan-Jwr-Jcc-Jec(6)Jsn;Jan;Jwr;Jcc;Jec7486:Jsn,James[22]:Jsn=0(1-Rs)Ca(7)0,W/m2;;Rs;CaJanStefan2Boltzmann:Jan=a(Ta+273)4(8)Stefan2Boltzmann,=516710-8W/(m2K4);Ta;a,Wunderlich[23]:a=0193710-5(Ta+273)4(1+0116C2l)(9)Cl:Jwr=w(Tw+273)4(10)w,w=0197[22];TwRyan&Harleman[24]:Jec=(6189+3107UW)(es-ea)(11)UW;es,es=6111exp17127TW23713+TW;ea,ea=hr6111exp17127Ta23713+Ta,hrJames[22]:B=JccJec=0161PaPTw-Taes-ea(12)Pa;P(12)CFD,Wells[5]2,:(vkC),,I:Iuuavg=0116(ReDH)-1/8(13)Re,Re=DHv,DH,m,DH=4Ax;v,m/s;,m2/s;A,m2;x,m0,,,,(6)(12)3Fluent6,,,84818:Wells[5](1)0104m3/s,2000mg/L,40%,1317,1016h40%,01056m3/s,01016m3/s,0104m3/s(1)1:1Table1Parametersinnumericalsimulation286186K(1317)015(50%)270196K(-212)113m/s958mb0105(5%)019113e-04111315kg/m3210m111315kg/m310m(1317)[22]9991286kg/m3918m/s222,233Fig13Comparisoncalculatedtemperaturecontourofthereferencecasewithexperimentalresult2Fig12Calculatedflowpatternandvelocityvectorillustrationofthereferencecase,,,,,,3,[5],,,,4,,4,9486:4Fig14Comparisonofcalculatedsludgedistributionofthereferencecasewithexperimentalresult,4[5](),1027000mg/L10m,,15m,4,Gr/Re2Gr,Re,Gr/Re2[25]Gr/Re2=(gTL)/u2(14)g;;T;L;uFr2pFrp,Fr2p[25]Fr2p=u2/(gh/)(15)h;;(14)(15),Fr2pGr/Re2,Fr2pGr/Re2=gTLu2u2gh/=TLh/(16),=0100013,277136K,T=286186-277136=9150K,L=10110m,h=4160m,=114121g/L,=1113150g/LFr2pGr/Re2=01031,,,,,,(16),,,,,Fr2pGr/Re24,Boussinesq,,:05818(1)Boussinesq,k2;(2),,;(3),;(4)Fr2pGr/Re2,,:[1],,.PHOENICS[J]1,2005,31(12):63-661[2]DeiningerA,HolthausenE1VelocityandSolidsDistributioninCircularSecondaryClarifiers:FullScaleMeasurementsandNumericalModelling[J]1WatRes,1998,32(10):2951-29581[3]Krebs1SuccessandShortcomingsofClarifierModelling[J].WarterScienceandTechnology11995,31(2):181-1911[4]McCorquodaleJA,ZhouS1Effectsofhydraulicandsolidsloadingonclarifierperformance[J]1JHydrRes,1993,31(4):461-4771[5]WellsSA,LaLiberteD1Wintertemperaturegradientsincircularclarifiers[J]1WaterEnvironmentResearch,1998,70(7):1274-12791[6]BobDC1ComputationalFluidDynamicsofSettlingTanks:DevelopmentofExperimentsandRheological,SettlingandScraperSubmodels[D]1Belgium:UniversityofGhent,20031[7]RittmannBE,McCartyPL1EnvironmentalBiotechnology:PrinciplesandApplications[M]1NewYork:McGraw-Hillcompanies,20011[8]EkamaGA,BarnardJL,GnthertFW,etal1Secondarysettlingtanks:theory,modelingandoperation[M]1London:IAWQScientificandTechnicalReport,1997.[9]LarsenP1Onthehydraulicsofrectangularsettlingbasins,experimentalandtheoreticalstudies[R].Lund:LundUniversity,Reportno11001119771[10],,.1,2003,19(1):43-451[11]Taebi2HarandyA,SchroederED1Formationofdensitycurrentsinsecondaryclarifier[J]1WatRes,2000,34(4):1225-12321[12]AndersonNE1Designofsettlingtanksforactivatedsludge[J]1SewageWorksJournal,1945,17(1):50-651[13]ZhouS,McCorquodaleJA,GodoAM1Shortcircuitinganddensityinterfaceinprimaryclarifiers[J]1JournalofHydraulicEngineering,1994,120(9):1060-10801[14]GodoM,McCorquodaleJA1Effectofdiurnaltemperaturevariationonthehydraulicsofclarifiers[J].CanJCivEng,1991,18(6):1084-10871[15]ZhouS,McCorquodaleJA1ModelingofRectangularSettlingTanks[J]1JournalofHydraulicEngineering,1992,118(10):1391-14001[16]KaramaAB,OnyejekweOO,BrouckaertCJ,etal1Theuseofcomputationalfluiddynamics(CFD):techniqueforevaluatingtheefficiencyofanactivatedsludgereactor[J]1WatSciTech,1999,39(10-11):329-3321[17]KrebsP,ArmbrusterM,RodiW1Laboratoryexperimentsofbuoyancy2influencedflowinclarifiers[J]1JournalofHydraulicResearch,1998,36(5):831-8511[18]AlonsoGriborio1Secondaryclarifiermodelingamultiprocessapproach[D]1NewOrleans:UniversityofNewOrleans,USA,20041[19]SchillerL,NaumannZZ.VerDeutschIng[M].1935,77:3181[20]RanzWE,MarshallWR1EvaporationfromDrops,Part[J]1ChemEngProg,1952,48(3):141-1461[21]RanzWE,MarshallWR1EvaporationfromDrops,Part[J]1ChemEngProg,1952,48(4):173-1801[22]JamesLM,StevenC1McCutcheon1Hydrodynamicsandtransportforwaterqualitymodeling[M]1London:Lewispublishers,1999.352-3671[23]WuderlichWO1Heatandmasstransferbetweenawatersurfaceandtheatmosphere,InternalMemorandum[R]1Norris:Tennesseevalleyau2thorityengineeringlab,19681[24]RyanPJ,HarlemanDRF1Analytifcalandexperimentalstudyoftransientcoolingpondbehavior[R]1MassachusettsInstofTech:ParsonsLabforwaterresouresandhydrodynamics,19731[25]YaoY,XieT1HandbookofChemistryandPhysics[M]1Shangha