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-   -   UDF to output the modeling? (http://www.cfd-online.com/Forums/fluent/28775-udf-output-modeling.html)

Fluent Newbee August 2, 2001 00:38

UDF to output the modeling?
 
Hi, I am struggling Newbee to Fluent and I got a lot of help from guys all over the world. Getting to the point, I managed to model a tank flow with baffle inside.

Now I need to produce output file (eg. x-velocity vs grid x coordinate) in "text format".(so that I can further the analysis on the result with my own made program). I tried XY plot in the menu but it takes me forever because I need to generate wide variety of data files in every single node.

I think I have to use macro or UDF but i have no idea where to start. Can you be kind enough to give me guide and some reference?

Thanks million in advance.

P.S : the flow is steady


david August 4, 2001 00:54

Re: UDF to output the modeling?
 
A) Write a script that will read your case and data file and create lots of planes and lines and write all the plots. B) On sort all the data by sort oldfile> newfile C) Postprocess using any software you know.

By the way, what model did u use for ur tank with baffle inside ?

DC

Fluent Newbee August 8, 2001 02:10

Re: UDF to output the modeling?
 
Thanks very much to pay attention to my post. I used k-e turbluence model, set the energy enabled and employed the defalut parameters. I didn't use VOF. I set the influent as a velocity inlet and output as a pressut outlet. (and in the Boundary condtion, turbluence intensity and hydraulic diameter were specified)

I set the free-surface as a wall because I am intrested in the flow in the tank itself. The simplfied model seems to make some sense from an engineer's point of view.

If you need more information, let me know.

By the way, I am still wodering how to make a script to do the job. No idea. Do you mean using some macros?? I would be very appreciative if you can give me some exaple and reference. Thanks in advance.


david August 11, 2001 06:07

Re: UDF to output the modeling?
 
A) To write a script file, try to start scrip writing,, FILE>WRITE>START SCRIPT,, B) now read the case/data file, run for 1 iteration, plot all the curves u want, save,, write,, all the plots C) FILE>WRITE>STOP SCRIPT. D) open the scrip file and modify the no of iteration to whatever u want. E) Run the scipt file (script_1) with -g command F) you need to modify the script file according to ur needs.

If you need more info, pls let me know.

Some questions to you: 1) Don't you think the wall BC on the top will efect the mixing behaviour inside (not much though) 2) How did u choose 'turbluence intensity' ? in the BC? DC

fluent newbee August 22, 2001 03:45

Re: UDF to output the modeling?
 
Thanks very much for paying attention to my humble post. I am working on the script and I think I will get it right sooner or later. I owe you a big time. With a bit of a luck I can simplfy the process of changing script.

I will ask additional assistance if I face some tricky situaltion. And the answer to your question ; 1) i asked many guys on the forum and they seem to agree the simplified model reflect the real world but I need to verify it with various methods. And your suggestion make sense, especially considering friction on the wall-set free surface. So I ignore the wall friction on free surface. The strange thing is that either I enable friction or not, the result seems constant. I believe because the flow is near laminar and plug flow (inlet velocity is apprx. 1cm/sec)

2)I refer to the fluent manual and get some idea about hydrolic diameter and turbluence intensity. I figure the flow has fairly low turbluence, so I go for 10%. Of course it's not perfect and mathmatical but I compared the model with sedimentation chamber experiment data table. There was some deviance but negligable. I need to further the expeirment to back up the model and I will adjust the parameter to reflect the model.

One other, I will open up a web page and I will post the model and the Fluet model results. Your comment, suggestion and constuctive criticsm is welcome. Thanks



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