residual in fluent

This is one of the best questions that anybody has posed in a while. As you've seen, it is sometimes not simple to declare convergence. Something that may help get the residuals down more, is to switch to double precision, and tweaking relaxation parameters may also help. Also, you need to consider the differencing scheme that you are using, and how accurate your initial flow field was. Something that sometimes helps is to get 0.0001 convergence on first order upwind differencing first, and then switch to higher order to see what it does. With external flows, where the initial flow field is normally a very good solution everywhere except near the body, it may also be difficult to get the requisite 0.001 convergence. For other flows 0.001 may not even be good enough. Take a very good look at how your surface integral changes with more iterations, sometimes if you really zoom in (in terms of y-axis scale), you can readily identify a damped oscillation, which is a good indication that you are "straddling" a converged answer. As last resort (or maybe that should be first?), work on your grid quality. If you have a number of skew or very high aspect ratio cells, perhaps away from your surface of interest, it may not affect your surface integral, but could affect the residuals.

http://www.cfd-online.com/Forums/fluent/44710-convergence-residuals.html

Residual

The residuals are the error magnitudes for equations as iterations progress. The equations include the governing equations; I.e. the Navier-Stokes momentum equations for each direction (x, y, and z if 3d, or just x and y if 2d), the continuity equation (conservation of mass), and if heat transfer is applicable, the energy equation. The equations may also include equations of the turbulence model defined under models-viscous. The residual is the difference between the previous result and the current result. As these errors are decreasing the equation results are reaching values that are changing less and less. This is what is known as convergence. That is the solutions are converging. If these errors begin to increase, the solution is then said to be diverging. Let me give a simplified example of convergence: Initial value = 2, 1st iteration value = 1.5 (residual value is equal to 2 - 1.5 = .5), 2nd iteration value = 1.2 (residual value = 1.5 - 1.2 = .3), 3rd iteration value = 1.05 (residual value = 1.2 - 1.05 = .15),... 1000th iteration value = 1.00001, and 1001th iteration value = 1.000005 (residual value = .00001 - .000005 = .000005). Perhaps the solution is converging to a value of 1. An opposite trend could be given as an example of divergence. A solution can converge and then diverge or vica versa. Does this help? Is my explanation clear and accurate?

http://www.cfd-online.com/Forums/fluent/28009-residuals.html

ansys fixed

what the hell.
today morning wake up fixed the flexnet problem for ansys.
https://johnkaisercalautit.wordpress.com/2013/02/14/how-to-fix-ansys-workbench-flexlm-error/
Step-by-step guide:

1. Run Server ANSLIC_ADMIN utility (as administrator)

2. Click Stop the ANSYS, Inc. License Manager

3. Open command prompt and enter netstat -a. Scroll down and you should find port 1055 in use.

4. From the ADMIN Utility, click Specify the License Server Machine

5. Click Edit Selected Server Machine

6. Change ANSYS FLEXlm port number to any port number other than 1055 (ex. 1056) and click OK

7. Go to the folder \Program Files\ANSYS Inc\Shared Files\Licensing and open license.dat using notepad. Change the port no. to the one you set above and save.

8. From the Server ANSLIC_ADMIN utility, click Install the License File

9. Browse for the edited license.dat file

10. Click Start the ANSYS, Inc. License Manager

ansys fsi problem I

O.K .so recently stuck in mesh in ansys fluid structure interaction.the mesh in transient structure does not work well.
It looks like there is still a long way to go.
keep on pops up
error updating cell solution in the transient structural system.
i guess most probably will need some luck
This error mostly returned while you have intersecting bodies in your problem geometry. just one of those bodies should be meshed and the other ones should be used as "Body of influence" at least in one "Sizing" feather.

I hope this could solve your problem.
Good Luck
http://www.cfd-online.com/Forums/ansys-meshing/93314-problem-updating-mesh-workbench.html

another one
The target body that you want to scope to needs to be selected as patch conforming tetrahedron - if you don't do this it will not modify the meshing (To make target body patch conforming right click on mesh, select insert -> method -> select target body --> then select method tetrahedron)
http://www.cfd-online.com/Forums/ansys-meshing/96051-bodies-influence-settings-problem.html

Fluent line1: parse error.

ok, so today I start my fluent practice.
I write a UDF , but so sad , it does't work. It stuck in the 1st line where parse error found.

Luckily I am not the only one who suffered from this problem. and i found the solution.
http://www.cfd-online.com/Forums/fluent/126287-parse-error-udf-code.html

 fix it by changing the format from UNICODE to ASCII

How to change the format from unicode to ASCII, when you save the .c file in notepad, you will notice that that is a drop list where inside has unicode to ASCII option as shown below

just select the ASCII, then you will mostly fixed the error. 

hope it helps for those beginner. 

CFX

I believe my supervisor sure will ask it whether CFX + ansys got any limitation
it is
http://www.ansys.com/staticassets/ANSYS/Conference/Boston/downloads/Systems%20Coupling%20-%20Ian%20Lockley.pdf

realization

O.K.
so i decide to use CFX +ansys i need to master it in 3 days.

http://www.cfd-online.com/Forums/cfx/23526-fsi-fluent-ansys-fluent-cfx.html
else i will be fired.

so fluent+ansys cannot do two way,
so i use cfx +ansys according to link

sad to say it is only has it in ansys 13
http://www.cfd-online.com/Forums/ansys/90844-2way-fsi-ansys-workbench.html

http://www.xansys.org/forum/viewtopic.php?p=69818&sid=864c3cb62e79ad3320ed002da8704b3d
if he can complete everything in one week, me too.gambateh.

UDF in fluent

http://www.youtube.com/watch?v=D-16riuSmrA

UDF in fluent
http://202.118.250.111:8080/fluent/Fluent60_help/html/udf/node15.htm
1.7 A Step-by-Step UDF Example

There are seven basic steps you should follow to code a UDF and use it effectively in your FLUENT model:

1.
Define your problem.
2.
Create a C source code file.
3.
Start FLUENT and read in or set up the case file.
4.
Compile or interpret the C source code.
5.
Activate the UDF in FLUENT.
6.
Run the calculation.
7.
Analyze the numerical solution and compare to expected results.
To begin the process, you'll need to define the problem you wish to solve using a UDF (Step 1). For example, suppose you want to use a UDF to define a customized boundary profile for your problem. You will first need to define the set of mathematical equation(s) that describe the profile.

Next you will need to translate the mathematical equations (conceptual design) into a function written in C (Step 2). You can do this using any text editor. Save the file with a .c suffix (e.g., velocity_profile.c) in your working directory.

Once you have written your C function, you are ready to start FLUENT and read in or set up your case file (Step 3). You will then need to interpret, compile, and debug your C source code (Step 4), and then activate your function in FLUENT (Step 5). Finally you'll run the calculation (Step 6), analyze the results from your simulation, and compare them to expected results (Step 7). You may loop through this entire process more than once, depending on the results of your analysis. Follow the step-by-step process in the sections below to see how this is done.

Step 1: Defining Your Problem

The first step in generating and using a UDF in your FLUENT model involves defining your model equations.

Consider the turbine vane illustrated in Figure 1.7.1. An unstructured grid is used to model the flow field surrounding the vane. The domain extends from a periodic boundary on the bottom to an identical one on the top, a velocity inlet on the left, and a pressure outlet on the right.

anys fluent 的安装方法

我将MAGNiTUDE文件夹中的AP13.exe程序运行了，生成了一个license文件，拷入到C:\Program Files\Ansys Inc下面，并且把这个license拷入到fluent的license目录下面了，可还是不行。
难道要用fluent6.3的license？
回答
试试看，我没装ansys，一直用fluent
回答者： roof0506 | 一级 | 2011-7-28 15:05
不是把安排ap13.exe生成的license文件直接拷贝过去
而是要安装license server manager（先装ansys），安装过程中会提示指定license文件
你就指向你生成的文件就可以，它会再fluent（ansys）的licensing目录下生成
另外一个license.dat文件，这个才是它需要的
回答者： 爱尔兰好汉 | 二级 | 2011-7-30 10:47
先保证 ansys 的 license 服务状态正常
正常安装，再用LEGEND文件夹下的license.dat替换掉安装文件夹....\Fluent.Inc\license\ 下的license.dat就可以了，我是这么安装成功的。而且运行好好的，谢谢楼主


1 安装Fluent_install-ntx86-6.3.26.exe
2“程序”中先运行client license setup ，在enter the license server name中输入你的计算机名
3 将legend中的license.dat文件拷贝到“D:\Fluent.Inc\license”中覆盖license.dat文件，然后运行fluent即可。

装最后一步 注册那个取消掉 然后把授权文件拷贝到 l..目录

帮助文档需要另外安装，安装文件夹中有两个文件，一个是程序，一个是帮助

你可能是因为有中文路径，你把新建文件夹改成英文名字试试。

可以用啊，我装的是64位 win7 旗舰版，安装成功

high end cad computer website

high end computer website
http://www.thinkmate.com/System/HPX_XS8-1410/20811

http://www.xicomputer.com/

http://www.pcsforeveryone.com

Rental
http://www.rentit.biz/high-end-computer.htm

http://www.cadtutor.net/forum/showthread.php?54492-AutoCAD-2011-Workstation-Specs-Deals-Suggestions