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1、..毕业论文后台阶流场无网格法气体流场数值模拟jz*..jz*..摘要无网格法的研究历史较短,在严格的数学论证、计算效率、边界条件处理和工程应用实例等方面还不能与成熟的有限元法相媲美,更未形成有效的通用软件,但是与有限元等基于网格的值方法相比,无网格法具有许多独特的优势。实际工程中大量存在几何形状不规那么或急剧变化的区域,这些区域内流动的显著特点是流动边界层脱离,出现大尺度涡,速度梯度和脉动加大,导致集中的能量损失,详细获取其流场的信息具有实际的意义。后台阶流即属此类流动,常被用作算例来检验算法精度和稳定性。但是对于采用无网格法对于流场的数值模拟研究尚处于起步阶段,相对于有网格法,采
2、用无网格法进展后台阶流场的数值会呈现新的规律。本文就是尝试采用径向基函数为根底的无网格化法,通过软件程序来运行无网格化法进展数值模拟,然后与有网格化法〔Fluent〕的数值模拟比较,分析区别和结果,做出评估。首先本文对无网格法的产生和开展做一些简单的介绍;其次简单介绍无网格法的原理和分类,并对其中的几种典型无网格法进展了大体的介绍,为后面了解径向基函数法即配点型无网格法做一个铺垫;再次,有网格化法主要采用有限差分法,本文将对有限差分法的原理和步骤进展简单的介绍;然后用Fluent处理一个简单的工况;最后将其与无网格法得到的结果进展一个简单的比较,然后做出分析和评价。关键词:无网络法;
3、速度梯度;径向基函数;有限差分法;Fluent;配点型无网格法。jz*..jz*..ABSTRACTThehistoryofmeshlessmethodisshort,inthestrictmathematicaldemonstration,computationalefficiency,boundaryconditionsandengineeringapplication,itisalsonotcomparablewiththematurefiniteelementmethod.Itdoesalsonotformaneffectivegeneral-purposesoftware.
4、Butwhencomparedtogrid-basedvaluemethod,suchasfiniteelementmethed,meshlessmethodhasmanyuniqueadvantages.TherearealotofirregulargeometryordramaticchangesintheregioninPracticalengineering,thedistinctivefeatureoftheseregionsisthattheflowboundarylayerhasdetached,thenthelarge-scalevortexcomesalong,th
5、evelocitygradientandpulseincrease,resultinginacentralizedenergyloss,soobtainingtheflowfieldinformationisofpracticalsignificance.Thebackward-facingstepflowissuchaflow,oftenusedasexamplestotestthealgorithmaccuracyandstability,Butforthemeshlessmethodfornumericalsimulationoftheflowfieldisstillinits
6、infancyrelativetothegridmethod,meshlessmethodstepsofthevalueoftheflowfieldwillshowthenewlaws.Thisarticleistotryusingradialbasisfunctionbasedmeshlessmethodfornumericalsimulationbyusingthesoftwareprogram,andthencomparetheresultwiththegridmethod(byusingtheFluent)numericalsimulation,atlast,analyset
7、heirdifferencesandmakeaevaluation.Firstly,thisarticlewillgiveabriefintroductiontothefirstemergenceanddevelopmentofthemeshlessmethod;Secondly,ananotherbriefintroductiontotheprinciplesandstepsofthemeshlessmethodwillbemade.andafewint