简介:Dynamicfluid-solidinteractionsarewidelyfoundinchemicalengineering,suchasinparticle-ladenflows,whichusuallycontaincomplexmovingboundaries.Theimmersedboundarymethod(IBM)isaconvenientapproachtohandlefluid-solidinteractionswithcomplexgeometries.Inthiswork,Uhlmann’sdirect-forcingIBMisimprovedandimplementedonasupercomputerwithCPU-GPUhybridarchitecture.Thedirect-forcingIBMismodifiedasfollows:thePoisson’sequationforpressureissolvedbeforeevaluationofthebodyforce,andtheforceisonlydistributedtotheCartesiangridsinsidetheimmersedboundary.Amultidirectforcingschemeisusedtoevaluatethebodyforce.Thesemodificationsresultinadivergence-freeflowfieldinthefluiddomainandtheno-slipboundaryconditionattheimmersedboundarysimultaneously.Thismethodisimplementedinanexplicitfinite-differencefractional-stepscheme,andvalidatedby2Dsimulationsoflid-drivencavityflow,Couetteflowbetweentwoconcentriccylindersandflowoveracircularcylinder.Finally,themethodisusedtosimulatethesedimentationoftwocircularparticlesinachannel.Theresultsagreeverywellwithpreviousexperimentalandnumericaldata,andaremoreaccuratethantheconventionaldirect-forcingmethod,especiallyinthevicinityofamovingboundary.
简介:-Thedynamicbucklingofelasto-plasticcylindricalshellsunderaxialfluid-solidimpactisinvestigatedtheoretically.Asimplifiedliquid-gas-structuremodelisgiventoapproximatelyimitatetheproblem.Thebasicequationofthestructureisderivedfromaminimumprincipleindynamicsofelasto-plasticcontinuaatfinitedeformation,andtheflowtheoryofplasticityisemployed.Theliquidisincompressibleandthegasiscompressedadiabatically.Anumberofnumericalresultsarepresentedandthecharacteristicsofthebucklingbehaviorunderfluid-solidimpactareillustrated.
简介:Duringthedevelopmentoflowpermeabilityreservoirs.theinteractionbetweenfluidflowandrock-massdeformationisobvious.Onthebasisoffluidmechanicsinporousmediaandelasto-plastictheory.theauthorpresentsanequivalentcontinuummodeltosimulatefluidflowinfracturedlow-permeabilityoilreservoircoupledwithgeo-stress.Themodelnotonlyreflectstheporositychangeofmatrix,butalsothepermeabilitychangeduetotheopeningandclosingoffracture.Byanalyzingofsimulationresults,thechangesinporosityandpermeabilityandtheireffectonoildevelopmentarestudied.
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简介:Theflowcharacteristicsinaspouted-fluidbeddifferfromthoseinspoutedorfluidizedbedsbecauseoftheinjectionofthespoutinggasandtheintroductionofafluidizinggas.Theflowbehaviorofgas-solidphaseswaspredictedusingtheEulerian-Euleriantwo-fluidmodel(TFM)approachwithkinetictheoryforgranularflowtoobtaintheflowpatternsinspouted-fluidbeds.Thegasfluxandgasincidentanglehaveasignificantinfluenceontheporosityandparticleconcentrationingas-solidspouted-fluidbeds.Thefluidizinggasfluxaffectstheflowbehaviorofparticlesinthefountain.Inthespouted-fluidbed,thesolidsvolumefractionislowinthespoutandhighintheannulus.However,thesolidsvolumefractionisreducednearthewall.
简介:Densegas-particleflowsareencounteredinavarietyofindustriallyimportantprocessesforlargescaleproductionoffuels,fertilizersandbasechemicals.Thescale-upoftheseprocessesisoftenproblematicandisrelatedtotheintrinsiccomplexitiesoftheseflowswhichareunfortunatelynotyetfullyunderstooddespitesignificanteffortsmadeinbothacademicandindustrialresearchlaboratories.Indensegas-particleflowsboth(effective)fluid-particleand(dissipative)particle-particleinteractionsneedtobeaccountedforbecausethesephenomenatoalargeextentgoverntheprevailingflowphenomena,i.e.theformationandevolutionofheterogeneousstructures.Thesestructureshavesignificantimpactonthequalityofthegas-solidcontactandasadirectconsequencethereofstronglyaffecttheperformanceoftheprocess.Duetotheinherentcomplexityofdensegas-particlesflows,wehaveadoptedamulti-scalemodelingapproachinwhichbothfluid-particleandparticle-particleinteractionscanbeproperlyaccountedfor.Theideaisessentiallythatfundamentalmodels,takingintoaccounttherelevantdetailsoffluid-particle(latticeBoltzmannmodel)andparticle-particle(discreteparticlemodel)interactions,areusedtodevelopclosurelawstofeedcontinuummodelswhichcanbeusedtocomputetheflowstructuresonamuchlarger(industrial)scale.Ourmulti-scaleapproach(seeFig.1)involvesthelatticeBoltzmannmodel,thediscreteparticlemodel,thecontinuummodelbasedonthekinetictheoryofgranularflowandthediscretebubblemodel.Inthispaperwegiveanoverviewofthemulti-scalemodelingstrategy,accompaniedbyillustrativecomputationalresultsforbubbleformation.Inaddition,areaswhichneedsubstantialfurtherattentionwillbehighlighted.
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简介:AbstractBackground:It is still unclear what the minimal infusion volume is to effectively predict fluid responsiveness. This study was designed to explore the minimal infusion volume to effectively predict fluid responsiveness in septic shock patients. Hemodynamic effects of fluid administration on arterial load were observed and added values of effective arterial elastance (Ea) in fluid resuscitation were assessed.Methods:Intensive care unit septic shock patients with indwelling pulmonary artery catheter (PAC) received five sequential intravenous boluses of 100 mL 4% gelatin. Cardiac output (CO) was measured with PAC before and after each bolus. Fluid responsiveness was defined as an increase in CO >10% after 500 mL fluid infusion.Results:Forty-seven patients were included and 35 (74.5%) patients were fluid responders. CO increasing >5.2% after a 200 mL fluid challenge (FC) provided an improved detection of fluid responsiveness, with a specificity of 80.0% and a sensitivity of 91.7%. The area under the ROC curve (AUC) was 0.93 (95% CI: 0.84-1.00, P < 0.001). Fluid administration induced a decrease in Ea from 2.23 (1.46-2.78) mmHg/mL to 1.83 (1.34-2.44) mmHg/mL (P = 0.002), especially for fluid responders in whom arterial pressure did not increase. Notably, the baseline Ea was able to detect the fluid responsiveness with an AUC of 0.74 (95% CI: 0.59-0.86, P < 0.001), whereas Ea failed to predict the pressure response to FC with an AUC of 0.50 (95% CI: 0.33-0.67, P = 0.086).Conclusion:In septic shock patients, a minimal volume of 200 mL 4% gelatin could reliably detect fluid responders. Fluid administration reduced Ea even when CO increased. The loss of arterial load might be the reason for patients who increased their CO without pressure responsiveness. Moreover, a high level of Ea before FC was able to predict fluid responsiveness rather than to detect the pressure responsiveness.Trial registration:ClinicalTrials.gov, NCT04515511
简介:Abundantfluid-meltinclusionsarefoundintheaegirine-augite-baritepegmatiteandcarbonatiteveinsintheMianningREEdeposit,Sichuan,Theyweretrappedinearlystagefluoriteandquartzfromasalt-meltsystemattemperatureshigherthan5000℃,Meanwhile,fluidinclusionsarealsopresentinalrgeamountsinbastnaesite.Homogenizedbetween150and270℃,theseinclusionsarethoughttoberepresentativeofthephysico-chemicalconditionsofREEmineralization.TheseresultsshowthattheMianningREEdepositisoftypicalhydrothermalorigindevelopedfromasalt-meltsystem.
简介:Laminarheattransferproblemisanalyzedforadiskrotatingwiththeangularspeedωinaco-rotatingfluid(withtheangularspeedΩ).Thefluidisswirledinaccordancewithaforced-vortexlaw,itrotatesasasolidbodyatβ=Ω/ω=const.Radialvariationofthedisk’ssurfacetemperaturefollowsapowerlaw.Anexactnumericalsolutionoftheproblemisobtainedbasingontheself-similarprofilesofthelocaltemperatureoffluid,itsstaticpressureandvelocitycomponents.NumericalcomputationsweredoneatthePrandtlnumbersPr=1(?)0.71.Itisshownthatwithincreasingβbothradialandtangentialcomponentsofshearstressesdecrease,andtozerovalueatβ=1.Nusseltnumberispracticallyconstantatβ=0(?)0.3(andevenhasapointofamaximuminthisregion);Nudecreasenoticeablyforlargerβvalues.
简介:Thesolid-phasesynthesisofisoxazolineson2-polystyrylsulfonamidoethanolresinisreported.2-Polystyrylsuifonamidoethanolresin1wasreactedwithacryloylchloridetoafford2-polystyrylsulfonylamidoethylacrylateresin2,whichwasfurtherreactedwithbrominatedaldoximesby[3+2]cycioadditiontogiveisoxazolineresin4.Resin4wastreatedwithaqueous6mol/LHCIsolutiontoobtainisoxazolinesingoodyieldandpurity.
简介:Anewflowtheoryisestablishedthroughtheobjectivityrequirementonthefluiddynamics.Itwasknownthatinhomogeneousfluidmotiongaverisetoviscousforcewhiletheselectionofobserversondifferentspace-timepointswouldchangesuchaninhomogeneouscharacter.Therefore,whentheviscousforcewasconsideredasanobjectiveexistenceforeigntotheselectionofobservers,theforminvariancesofviscousforceandmomentumequationunderlocalrotationtransformationrequiredanewdynamicfield,namelythevortexfieldtobeintroduced.ThenthedynamicalequationsofallflowfieldswereobtainedthroughconstructingtheLagrangiandensityoffluidsystemandusingthevariationalapproachofenergy.
简介:WithoutsimplifyingtheN-SequationsofGermano’s,westudytheflowinahelicalcircularpipeemployingperturbationmethod.Athirdperturbationsolutionisfullypresented.Thefirst-second-andthird-ordereffectsofcurvatureкandtorsionтonthesecondaryflowandaxialvelocityarediscussedindetail.Thefirst-ordereffectofcurvatureistoformtwocounter-rotatingcellsofthesecondaryflowandtopushthemaximurnaxialvelocitytotheouterbend.Thetwocellsarepushedtotheouterbendbythepuresecond-ordereffectofcurvature.Thecombinedhigher-order(second-,third-)effectsofcurvatureandtorsion,arefoundtobeanenlargementofthelowervortexofthesecondaryflowatexpenseoftheupperoneandaclockwiseshiftofthecentersofthesecondaryvorticesandthelocationofmaximumaxialvelocity.Whentheaxialpressuregradientissmallenoughorthetorsionissufficientlylargerthanthecurvature,thelocationofthemaximalaxialvelocityisneartheinnerbend.Theequationofthevolumefluxisobtainedfromintegratingtheperturbationsolutionsofaxialvelocity.Fromtheequationthevalidityrangeoftheperturbationsolutionsinthispapercanbeobtainedandtheconclusionthatthethreetermsoftorsionhavenoeffectonthevolumefluxcaneasilybedrawn.Whentheaxialpressuregradientislessthan22.67,thevolumefluxinahelicalpipeislargerthanthatinastraightpipe.
简介:在这份报纸,稳固的粒子在的聚类的行为一二维(2D)liquidsolid使流体化床被使用费用学习测量并且处理技术的联合设备(电荷耦合器件)成像并且被分数维的分析描绘。在2Dliquidsolidfluidised床的稳固的粒子的分发不是制服和稳固的粒子的组织工会行为的电荷耦合器件图象表演在现在的试验性的条件下面被观察。稳固的粒子搬到在其配置经常在水平海滨形式的组或簇使流体化床的2D。簇的框分数维图形尺寸在2Dliquidsolid想象有与稳固的粒子直径和表面的液体速度的增长稳固的劫盗和还原剂升起的使流体化床的增加。在给定的稳固的劫盗和稳固的粒子尺寸,更轻的粒子显示出更小的分数维的尺寸。
简介:Thispaperdescribesanovelsharpinterfaceapproachformodelingthecavitationphenomenainincompressibleviscousflows.Aone-fieldformulationisadoptedforthevapor-liquidtwo-phaseflowandtheinterfaceistrackedusingavolumeoffluid(VOF)method.PhasechangeattheinterfaceismodeledusingasimplificationoftheRayleigh-Plessetequation.Interfacejumpconditionsinvelocityandpressurefieldaretreatedusingalevelsetbasedghostfluidmethod.Thelevelsetfunctionisconstructedfromthevolumefractionfunction.Amarchingcubesmethodisusedtocomputetheinterfaceareaattheinterfacegridcells.Aparallelfastmarchingmethodisemployedtopropagateinterfaceinformationintothefield.Adescriptionoftheequationsandnumericalmethodsispresented.Resultsforacavitatinghydrofoilarecomparedwithexperimentaldata.
简介:Thepaperstudiestheproblemoffluidflowandfluidshearstressincanaliculiwhentheosteonissubjecttoexternalmechanicalloadingandbloodpressureoscillation.Thesingleosteonismodeledasasaturatedporoelasticcylinder.Solidskeletonisregardedasaporoelastictransverselyisotropicmaterial.Togetnear-realisticresults,boththeinterstitialfluidandthesolidmatrixareregardedascompressible.BloodpressureoscillationintheHaveriancanalisconsidered.Usingtheporoelasticitytheory,ananalyticalsolutionoftheporefluidpressureisobtained.Assumingthefluidincanaliculiisincompressible,analyticalsolutionsoffluidflowvelocityandfluidshearstresswiththeNavier-Stokesequationsofincompressiblefluidareobtained.Theeffectofvariousparametersonthefluidflowvelocityandfluidshearstressisstudied.更多还原