在workbench中用CFX对流体分析，但是我的流体是静止的，怎么设置入口出口啊，没有入口出口啊_百度知道
在workbench中用CFX对流体分析，但是我的流体是静止的，怎么设置入口出口啊，没有入口出口啊
模型是一个圆柱形探头在静止液体中振动
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流体不懂啊
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出门在外也不愁查看: 2577|回复: 9
cfx pre 出现 “2 isolated fluid regions”的问题
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用ansys作稳态电磁场的分析比较多(磁场分布,电磁力分布),也用过ansys作了简单的流体计算(0.5m/s 粘性湍流).&br /&&br /&现在想用在用ansys计算得到电磁力(大小在几十N/m^3)的条件下,使用cfx计算流体。&br /&&br /&研究对象为：两层高温熔体，上层为熔盐（5cm厚，15m长），下层为铝液（20cm厚，15m长）。步骤：在ansys中划分网格计算，导出网格文件和电磁力；使用CFX pre读入网格文件，定义两层流体性质（粗略都认为是铝液），定义domain等，最后倒入电磁力（只考虑x方向，本来想读入三个方向的，不会），在CFX solver求解，出现了一下错误：&br /&&br /&& && && && && && &2 isolated fluid regions were found in domain Domain 1&br /&&br /& 处理提示：&br /& If the isolated regions do not have the pressure level set either&br /& by the boundary conditions or using a reference pressure equation,&br /& you may encounter severe robustness problems.&br /&&&&br /& This situation may have arisen because a domain interface was not&br /& properly defined during problem setup.&&nbsplease carefully check&br /& the setup.&br /&&&&br /& The solver will stop now and write a results file.&&The isolated&br /& regions can be visualised in CFX Post by making plots of the &br /& variable &Isolated Volumes&.&br /&&&&br /& If you are sure that the pressure level is set in each isolated&br /& fluid region then you can force the solver to turn off this check&br /& by setting the expert parameter &check isolated regions = f&.&br /&&br /&由于对CFX post不熟，未能解决问题。&br /&&br /&望高手指教。&br /&&br /&谢谢
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幾個動作要作:&br /&1. quit current cfx5&br /&2. 設定系統環境變數CFX5_NO_CONSTANT_PHYSICS, 其值為T&br /&3. 照目前的設定(你若未設定step2的變數), 你是無法設定兩種不同流體的,你應再檢查一次你的domain properties&br /&4. 因為default, cfx認為所有流體需相通的,所以你若是有不相貫通的流體, 應該在 expert parameter專家變數選項中&br /&找一找, 設定&check isolated regions = f&.&br /&5. restart cfx5
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找到 expert parameter中的&check isolated regions &并设定为f.可以进行计算了.&br /&&br /&版主,如何把三维电磁力(fx,fy,fz)作为源项使用user fuction导入到cfx中. 就这个问题我参考了CFD-online 上的说明,但不是很懂.另外,ansys生成的有限元网格导入到cfx后,编号应该不会变吧,个人认为,cfx是以三维坐标为量度.想请版主解释一下cfx中单元的问题.&br /&&br /&谢谢&br /&&br /&&br /&附CFD-online论坛关于导入电磁力的帖子&br /&&br /&gtosted By:& & & & Dimitriy &Send Email& 提问者&br /&&br /&Date:& & & & Fri, 17 Dec
a.m.&br /&Hi every one &br /&Let me explain my problem. For example I have a cubic volume (domain). All of the cube?s boundaries are walls with different temperatures so that the fluid flow is entirely within the domain and driven by thermal convection. (I do not have inlet, outlet?.. boundaries, there are only walls with different temperature.) I need to import a distributed body force which operates within the domain that tries to change the convection motion of the liquid. Please tell me how to implement the force data in the CFX &br /&________________________________________&br /&gtosted By:& & & & Rui&br /&Date:& & & & Fri, 17 Dec
a.m.&br /&In Response To:& & & & Force import in CFX (Dimitriy)&br /&&br /&Hi, &br /&You have to create a sub-domain, which shall include the whole domain. Then create a momentum source, which you may set as a constant or as an expression function of the variables you want. &br /&May I ask what force is that, trying to change the convection motion? &br /&Regards, &br /&Rui &br /&________________________________________&br /&gtosted By:& & & & Dimitriy &Send Email&&br /&&br /&Date:& & & & Fri, 17 Dec
a.m.&br /&In Response To:& & & & Re: Force import in CFX (Rui)&br /&&br /&Hi Rui &br /&Force ? electromagnetic Liquid ? liquid metal &br /&I have a date of force distribution as vector matrix (value and direction of force are different at different points of domain) it is not a constant or function. &br /&What shall I do in this situation? &br /&Regards, &br /&Dmytro &br /&________________________________________&br /&gtosted By:& & & & Ribeiro&br /&Date:& & & & Fri, 17 Dec
p.m.&br /&In Response To:& & & & Re: Force import in CFX (Dimitriy)&br /&&br /&Hi Dmitri &br /&You should define a User Function on CFX-Pre. Use the Option parameter Interpolation (Data Input). Then choose in interpolation Data Option Three Dimensional. Right-click on Coordinate-Value frame and choose Import... Indicate your file. &br /&You should be aware that your file must be in the CFX format. Read the documentation. &br /&Regards, &br /&Ribeiro &br /&________________________________________&br /&gtosted By:& & & & Dimitriy &Send Email&&br /&&br /&Date:& & & & Tue, 21 Dec
a.m.&br /&In Response To:& & & & Re: Force import in CFX (Ribeiro)&br /&&br /&Dear Ribeiro &br /&Thank you for your advice. &br /&Only I can not understand a dimension of momentum source. It is kg/m^2s^2 but force is kg*m/s^2. &br /&Dose it mean that in expression should be something else except force? &br /&Redards, &br /&Dmytro &br /&________________________________________&br /&Posted By:& & & & Rui&br /&Date:& & & & Tue, 21 Dec
p.m.&br /&In Response To:& & & & Re: Force import in CFX (Dimitriy)&br /&&br /&Hi, &br /&Thats's because the momentum equations have units of Force per unit Volume: (kg*m/s^2)/m^3=kg/m^2s^2. And body forces (as gravity) only make sense as force/volume. &br /&Regards and Merry Christmas, &br /&Rui &br /&________________________________________
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沒作過電場的問題!&br /&這個問題同plasma的分析嗎?若不導入Maxwell eq.,純利用momentum source 的話&br /&由Rui (同Glenn, Robin一樣,大牛一個!),解答可知它要利用設定等效的&br /&momentum source 加在流場中,不需要用到UserFortran,直接在momentum source中設定.&br /&(similar to use momentum source to simulate a fan)&br /&&br /&你說的&font color=&blue&&cfx中单元的问题&/font&, 不甚清楚你指?&br /&(CFX可吃structured or unstructured mesh!)&br /&&br /&另外UserFortran(CEL or JunctionBoxRoutine)需要你花時間下去研究的,很難說清楚的!&br /&&br /&
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在ansys中使用六面体网格划分实体,所以输出的网格文件cdb中都是六面体网格.把这些网格导入到cfx中后,1)它的编号会不会发生变化,2)它的坐标范围发生变化没有(看了一下cfx中模型的三个方向的范围,没有变化),3)力是有大小和方向的,从ansys中导出的力是三个方向的如fx,fy,和fz(它们都是单元的体积力),怎样把这三个方向的力输入到模型中去;cfx中的单元如何认出这些力是加在了单元的形状中心呢.&br /&&br /&太多问题了...&br /&&br /&&br /&望版主解答.
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你試一下轉到cfx中就知道mesh有無變化的,至於編號在cfx中並沒有關係的,它是採用finite volume,與ansys不同的&br /&cfx只能讀入網格吧(不知是否可讀入ansys其它data), 但是你的體積力要先建subdomain,然後在subdomain中加入三個方向的&br /&momentum source. 感覺你可能把結構分析的觀念套到流場分析了?&br /&&br /&You'd better study the tutorials of CFX first.
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谢谢版主&br /&&br /&好的,先学学tutorials
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离最开始的提问到现在，“用ansys计算得到电磁力(大小在几十N/m^3)的条件下,使用cfx计算流体”的顺序计算已经完成了。&br /&&br /&正如版主Kiddosuper和CFD-online上 高手所说，想把离散电磁力（非函数表达式）施加在cfx 流体计算中的&br /&&br /&&font color=&blue&&第一步：整理数据文件，每行格式为 x,y,z,fx,fy,fz，行数为单元总数量（ansys中），不需要题头；&/font&&br /&&br /&&font color=&blue&&第二步：在CFX中定义user function函数，使用Interpolation(DataInput)选项，依次填入坐标单位[m,m,m]及体积力单位[kgm^-2s^-2]，选三维数据插值Interpolation，然后导入文本数据文件，注意第四列与fx对应，依次类推；&/font&&br /&&br /&&font color=&blue&&第三步：定义包括domain域的subdomain，然后在其general momentum source下填入函数fx(x,y,z)，fy(x,y,z)，fz(x,y,z)，至此在CFX中耦合体积电磁力设置步骤结束&/font&。&br /&&br /&在CFX建模及输入材料，与具体问题相关，不赘述。希望上述方法对各位有帮助。&br /&&br /&感谢版主Kiddosuper对我的帮助。&br /&&br /&
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感謝, 問題解決了還不忘回來將心得寫下來. 好榜樣! 加分.
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这个例子不错，huaifeng_lw 能否把整个过程贴上来，让大家都学习学习。
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