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Pavan October 18, 2006 19:02

Writing out specific data from FLUENT

Consider this example. I have a rectangular domain in which I am solving for the flow. I have defined 4 points at some regular distances in the domain where I want to read out flow variables. Is there a way of may be writing a UDF somehow so that I can write say the temperatures at these 4 points at regular intervals of time to an out put file and appending the file every time? IF there is, is it also possible to get area averaged values for particular parameters? Any suggestion would be greatly appreciated. Thanks.


sach October 18, 2006 23:15

Re: Writing out specific data from FLUENT
you need a udf for the same

hirokata October 19, 2006 01:06

Re: Writing out specific data from FLUENT
Other people may have a better idea but I just use C functions. You can write pretty much any values to a file. I'll tell you, postprocecssing those files won't be easy, though.

Jason October 19, 2006 08:01

Re: Writing out specific data from FLUENT
Have you looked through the Surface monitors? There's a lot of options that are already built into Fluent. Define->Monitors->Surface Monitors... for any monitor you want a data file, turn on the "write" option. You can also plot them... and you can chose if you want to report based on iteration or time step... when you're turning on the iterations you can define a report increment. Otherwise, you can just write it every time step and filter it later on.

Hope this helps, and good luck, Jason

Pavan October 19, 2006 10:27

Re: Writing out specific data from FLUENT
Thanks for the answers guys. Jason, I did look at the surface monitors. It would have been great if it had a write option at specific time increments. Unfortunately it seems to be able to do it only at every iteration/time-step. And I need to save at something like once every 12000 time steps. So if I do it once every and try to filter the file, not only is it going to be very tedious but the file size will be huge also. I don't know if I am missing anything here. Any ideas? I was also looking at the execute macros. THe only problem is I need an area averaged value at a boundary and with the execute command I don't seem to be able to write an area averaged value to file. So I am still searching. Any ideas would be greatly appreciated. Thanks once again.


Jason October 19, 2006 11:26

Re: Writing out specific data from FLUENT
Well, if you're comfortable with programming, you could always write a script that will blow through your monitor file and only grab the points you want (I'm a big advocate of Perl...). Or if you don't care about residuals or anything in between when you're writing your data, you may be able to set a report interval when you define how many iterations (I know you can for steady state... unsteady, I'm not sure).

Beyond that, I think you're going to have to write a UDF (but that's more programming... and I'm not really sure how you'd go about it...).

Best of luck, Jason

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