CFD Online Logo CFD Online URL
Home > Forums > FLUENT

UDF file interpretation fails and several problems occurs

Register Blogs Members List Search Today's Posts Mark Forums Read

LinkBack Thread Tools Display Modes
Old   February 8, 2017, 09:38
Exclamation UDF file interpretation fails and several problems occurs
New Member
Join Date: Jan 2017
Posts: 6
Rep Power: 2
eliaskhan is on a distinguished road
Sponsored Links
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
 Error: %prf-set-var: invalid flonum
Founded answers are like
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
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!
eliaskhan is offline   Reply With Quote
Sponsored Links

Old   February 9, 2017, 11:10
Senior Member
Join Date: Nov 2013
Posts: 1,074
Rep Power: 14
pakk will become famous soon enough
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.)
pakk is offline   Reply With Quote


Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On

Sponsored Links

All times are GMT -4. The time now is 08:01.