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UDF file interpretation fails and several problems occurs

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Old   February 8, 2017, 09:38
Exclamation UDF file interpretation fails and several problems occurs
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elias
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Hello guys,

I am working on my 2D case about a sheet blade in a wind channel. Currently I am trying to integrate a UDF for my velocity profile.
The moment when I integrate it and when I want to start the Solution Initialization the problem of the Revesed Flow occurs.
I know it has been discussed a few times in other threads, I went through all of them but unfortunatley it did not give me the solution.

What I have already done for the reversed flow problem:
1. Changing the BC for my outlet from outflow to pressure outflow
2. Checking dimensions in x- and y direction
3- Changing my reference values for inlet , after that changing the reference values for my fluid zone (length)
4. Changing my turbulent coefficient
5. Correction of my turbulent length
6- Changing my nodes in ICEM at the OUTLET by setting them lower


Additionally to that, FLUENT gives me following error
Code:
 Error: %prf-set-var: invalid flonum
Founded answers are like
Code:
From numerical computation view point , the basic operations performed by computer arerepresented inside computer in what is called floating point numbers. The errors that are either  because of invalid numeric computation initiated by user or limitation of machine that is used arefloating point errors.
or reasons of different fluent versions like in this thread
Code:
https://www.cfd-online.com/Forums/fluent/37048-fluent-fuel-cell-model.html
I already searched on the internet for a suitable solution, but I was not successful.

You see, I tried not less things to get it done.


I hope somebody has a good suggetions or even a solution. Thank you all!
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Old   February 9, 2017, 11:10
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In general, if you see reversed flow warnings directly after initialization: ignore it!

Reversed flow is only a problem when this still happens in the converged solution.

But if you really have a velocity profile UDF at the boundary, are you sure that your UDF is giving a velocity that points at the right direction? If you apply this BC at an outlet, but your UDF velocity points inwards, then whatever you do in the rest of the model, you have a problem.

(Don't know about your additional problem.)
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