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1、个人收集整理勿做商业用途Ｆluent关于壁面设置中的Roughnｅsｓ Hｅigｈt与Ｒoughｎｅss CｏnｓtａntCsKsＳetting ｔheＲougｈnｅsｓPaｒaｍeｔersThｅ rougｈnessparamｅtｅrs aｒeintｈe Ｍoｍentum ｔabofｔｈe ＷallＤialog Box (ｓee Ｆigure 6.34: TheＷall DｉalogＢoｘfor MaranｇoniStreｓｓ），ｗhicｈis openedfroｍthe ＢounｄａryCondiｔiｏns TａskＰage （ａｓdｅsｃribeｄｉn Settｉ
2、ngCellZｏnｅanｄＢｏunｄarｙConｄitioｎs).To mｏdｅl theｗallrougｈneｓs effects,you musｔspecify twｏ rｏｕghnesｓpａｒａmeters: the RｏuｇｈｎeｓｓHeight, ，ａnｄthe RｏugｈnessConstａnt, ．Thedefaultrouｇhnesｓheight( )iszero，wｈichcｏrｒespondsｔｏsmｏｏth walｌｓ.Fortｈｅｒｏｕghneｓｓtotakｅｅｆfecｔ,yｏｕmustspecifｙ anoｎ-ｚerovalue foｒ
3、 .Foｒaunifｏrmｓand-grainroｕghnesｓ, tｈｅheigｈｔofthe sand－grainｃansiｍplybetａｋｅn ｆor .For anon－ｕniｆｏｒｍ ｓａｎd－ｇrain,ｈｏｗevｅr,themeanｄiａmeter（ )ｗｏuldbｅamorｅ meａｎinｇfulroｕgｈnｅssｈeiｇht.For otｈertyｐes ofrouｇhｎeｓｓ,an“equivａlent”saｎd-ｇｒａinroughｎｅｓs heｉghｔcｏuｌdbｅusｅｄfor . Theａboｖeapｐroacｈeｓaｒe ｏｎlyｒ
4、elevantifｔheheiｇhtｉs considered ｃonstａｎｔper surｆacｅ.Ｈowever,iｆthｅｒoughnessconstantorrougｈnesｓheｉghtisnｏtｃonstant,thenyoucanspecｉfyaprofilｅ （ｓeｅ Prｏfiles). Similａrlｙ,user-defiｎedfｕnｃｔionsmaybeuｓed todefine awallroughnｅsｓheｉｇhtthatiｓnotｃoｎｓｔanｔ.Ｆｏrｄｅtaiｌｓoｎ theformaｔof ｕsｅｒ-definｅd funｃtｉ
5、ｏnｓ, refeｒ toｔhe UDF Mａnual．个人收集整理勿做商业用途Chooｓinｇ aprｏperrｏugｈnｅssconstａnt ( ) isdictatedmａｉnlｙｂy ｔheｔypeoｆｔhｅgiveｎｒouｇｈness.Tｈｅdeｆault roughｎessconstant ( ）ｗａsdeterｍｉneｄｓotｈat,whenusｅd wｉth - ｔｕｒbuｌｅｎcｅmoｄeｌs，iｔreproｄuｃｅsNiｋuradse’s resisｔaｎcedａtａ ｆoｒpｉｐesroughenedｗithtiｇhtly－pａcked,u
6、nｉformsanｄ-gｒａin ｒoｕghｎess.Youｍaｙ nｅｅdtｏａdｊｕstｔｈeroughneｓsｃｏnｓtaｎtwhｅｎｔhe roｕghness yoｕwantｔomｏdeldeparｔｓmｕch frｏｍuniformsaｎｄ－ｇｒaiｎ．Ｆorinsｔanｃｅ, there iｓsomeｅxｐerimenｔａｌeviｄeｎｃetｈａt,fｏrnｏn-ｕｎiｆormsand-gｒaｉｎs,ｒｉbs, ａｎdwire-meshｒoｕgｈｎess,ahighervalue( ）ismore ａppｒopriａte.Ｕnfortunａtely, ac
7、ｌear guiｄeｌinefｏrchoosiｎg for aｒｂitrarｙｔｙpesｏｆrougｈnessisnoｔaｖａilabｌe．Noｔｅ: Thｅ rouｇｈｗａll forｍuｌaｔionｕsｉngｔheshift inｔrｏｄucｅdin Equａtｉon ６–9３ elimｉｎateｓallrestｒictions withrespecｔtomeshresolutionｎearthewallandcａnthｅrefｏｒe bｅrunonarbｉｔｒaryfinｅｍeshes．两个参数的含义是:rｏuｇｈneｓsｈeｉgｈt粗糙度
