简介:利用数值模拟的方法对冷气轴向通流旋转盘腔的流动过程进行了研究.研究发现,对应一进口冷气的雷诺数,存在一临界瑞利数(Rac),高于该瑞利数(Ra),流动出现不稳定现象,且Ra越大,不稳定行为越严重.对于特例,盘腔内的流动可以看成是由类Rayleigh-Benard对流和强迫对流两个区域构成,两个区域通过能量和质量交换相互影响,流动随着Ra的增加从稳态发展为非稳态;采用频谱图分析的方法对数值解的不稳定性进行定性分析,结果显示随着Ra的增大,数值解经历了从稳定解到分贫的周期性不稳定和准周期不稳定的发展过程.离心浮升力引起的类Rayleigh-Benard对流是造成流动从稳定到不稳定发展的重要原因,哥氏力的存在恶化了不稳定过程.
简介:采用变物性格子Boltzmann通量求解器(VPLBFS)研究了Rayleigh-Benard热对流.以超临界流体为例,采用VPLBFS的简化形式和标准形式分别得到了通常关注的基于Boussinesq假设的常物性解,只考虑部分物性变化的基于partialBoussinesq假设的PBA解,以及考虑流体全部物性变化的变物性解,分析了non-Boussinesq效应对Rayleigh-B6nard热对流的影响,讨论了不同温差条件下的non-Boussinesq效应.研究结果表明:non-Boussinesq效应对超临界流体的Rayleigh-B6nard热对流有非常显著的抑制作用,论证了在研究热对流时考虑流体全部物性变化的必要性.
简介:利用重合度理论,研究一类具有奇性的p-Laplacian-Rayleigh方程,获得其周期正解存在性新的充分条件,推广和改进了已有文献中的相关结论.
简介:利用Mawhin重合度拓展定理研究一类具偏差变元的Rayleigh方程x″(t)=f(x′(t))+g(x(t-τ(t,x′(t))))+p(t)的周期解问题,并得到一些有意义的结果.
简介:1.IntroductionThroughoutthispaperweshallusethefollowingnotation.RmxnandCoxsdenotethesetsofrealandcomplexmxnmatrices,respectively,R'andC'denotethesetsofrealandcomplexn-dimentionalcolumnvectors,respectively.ThesuperscriptHmeanstheconjugatetransposeofma...
简介:Someofthemathematicalpropertiesoftheinterfacebetweentwoincompressibleinviscidandimmisciblefluidswithdifferentdensitiesundertheinfluenceofaconstantgravityfieldgareinvestigated.ThepurposeofthispaperistoprovethatlinearlyunstablemodesforRayleigh-Taylorinstabilitiesgivebirthtononlinearinstabilitiesforthefullnonlinearsystem.Themainingredientisageneralinstabilitytheoreminananalyticframeworkwhichenablesustogofromlineartononlinearinstabilities.
简介:主要运用Mawhin重合度拓展定理研究了一类广义平均曲率Rayleigh方程(x'(t)/(1+x'2(t))+f(x'(t))+g(t,x(t))=e(t)周期解存在性与唯一性问题,得到了周期解存在性与唯一性的相关新结果。
简介:应用LeraySchauder不动点定理,研究了一类具时滞的Rayleigh型泛函微分方程:x″(t)+f(x′(t))+g(x(t-τ(t)))=e(t)的反周期解问题,得到了反周期解存在的新的结果。
简介:Inordertobetterassesstheperformanceofwirelesscommunicationsystems,itisdesirabletoproducemultipleRayleighfadingenvelopeswithspecifiedcorrelations.Inthispaper,weanalyzetheoreticallyaprocedurewhichgeneratescorrelatedGaussianrandomvariablesfromindependentGaussianrandomvariablesandgiveaphysicalexplanationforthelimitationofthisprocedure.Then,basedonsomeuncorrelatedRayleighfadingenvelopes,asimplebutefficientprocedureforgeneratinganarbitrarynumberofcross-correlatedRayleighfadingenvelopesisproposed.Simulationresultsandcomputationalcomplexityanalysisarepresented,whichshowthattheproposedmethodhassomeadvantages,suchashighaccuracy,lowcomputationalcomplexityandeasyimplementation,overtheconventionalsimulationmethod.
简介:Inthispaper,weinvestigatetheRayleigh-Taylorinstabilityproblemfortwocompressible,immiscible,inviscidflowsrotatingwithaconstantangularvelocity,andevolvingwithafreeinterfaceinthepresenceofauniformgravitationalfield.FirstweconstructtheRayleigh-Taylorsteady-statesolutionswithadenserfluidlyingabovethefreeinterfacewiththesecondfluid,thenweturntoananalysisoftheequationsobtainedfromlinearizationaroundsuchasteadystate.Inthepresenceofuniformrotation,thereisnonaturalvariationalframeworkforconstructinggrowingmodesolutionstothelinearizedproblem.Usingthegeneralmethodofstudyingafamilyofmodifiedvariationalproblemsintroducedin[1],weconstructnormalmodesolutionsthatgrowexponentiallyintimewithratelikeet■whereξisthespatialfrequencyofthenormalmodeandtheconstantcdependsonsomephysicalparametersofthetwolayerfluids.AFouriersynthesisofthesenormalmodesolutionsallowsustoconstructsolutionsthatgrowarbitrarilyquicklyintheSobolevspaceH~k,andleadstoanill-posednessresultforthelinearizedproblem.Moreover,fromtheanalysisweseethatrotationdiminishesthegrowthofinstability.Usingthepathologicalsolutions,wethendemonstratetheill-posednessfortheoriginalnon-linearprobleminsomesense.
简介:近似却分析的答案粘滞Rayleigh-Taylor不稳定性(RTI)最近广泛地由于它的清澈在理论、数字的调查被使用了。在这份报纸,生长率为的一个修改分析答案粘滞不可压缩的液体的RTI基于一个近似方法被获得。它的精确性数字地被验证显著地为不同粘性比率和Atwood数字在整个波浪数字范围与以前的那比较被改善。而且,这个答案被扩展为粘滞包括集中散开效果的RTI。
简介:ThemodelingmethodologiesandcalculationofdynamicresponseofundergroundstructureunderRayleighwavesisinvestigatedinthispaper.FirstthefreefieldresponsesunderRayleighwavesareanalyzedandthenumericalresultsagreewellwiththetheoreticalresults.Then,theapproximateRayleighwavesareputforwardbasedonthepreliminaryre-search,andRayleighwavefieldisobtainedthroughfastFouriertransformtechnique.Takingautilitytunnelasanexample,itsdynamicresponsesunderRayleighwavesiscalculatedbyABAQUS.Theresultsdemonstratethatbendingdeformationisthemaincomponentofstructuraldeformationandthedeformationatthetopofthestructureisabouttwiceasmuchasthatatbottomofthestructure.Theeffectofsoil-structureinterfaceandtheburieddepthofundergroundstructurearealsoinvesti-gatedviaparameteranalysis.Fortheshallowburiedundergroundstructures,Rayleighwavescanbethekeyfactortocontroltheresponsesanddamageofthestructure.
简介:以便理解材料的粘弹性,这研究被进行了理论上学习粘弹性的瑞利波浪的繁殖特征。一个模型在粘弹性的中等表面上为超声的搏动的激光产生被介绍。指了凯尔文模型,频率方程和粘弹性的瑞利的正常排水量波浪被导出,分散和变细上的粘弹性的模量的影响被讨论。从理论计算,瑞利波浪的变细上的粘弹性的效果在它的分散上多于那,这被显示出。在弱粘性的情况中,粘弹性的瑞利波浪的变细与粘性模量直接成正比;效果砍变细上的粘性是多于体积粘性的大部分。粘弹性的瑞利波浪的短暂反应也用Laplace和Hankel倒置变换被模仿,它在对理论上的预言的好同意被显示出。模型为媒介的粘弹性的参数的决心提供一个有用工具。