UDF for degassing boundary condition

peaker007 · December 20, 2011, 04:02

I am doing simulation about bubble column which gas goes in from the bottom but outflow from the top of reactor. I have read some papers who treated the outlet as a degassing boundary condition. It illustrated as follows:
at the top of the reactor, an outlet boundary condition has
been used for the gas phase and a symmetry boundary condition
has been used for the liquid phase, this degassing condition
has been implemented through a user defined function.
I am not proficient about UDF, who can give me an example UDF for degassing boundary condition or give me some advice about how to write the UDF.Thank you very much for your kindness.

ComputerGuy · December 29, 2011, 19:47

Peaker007,

Have a look at the Fluent 12 (or up?) UDF manual. Page 2-103 gives a full UDF listing of a degassing boundary condition.

Best,
ComputerGuy

peaker007 · December 29, 2011, 21:38

Quote:

Originally Posted by ComputerGuy

Peaker007,

Have a look at the Fluent 12 (or up?) UDF manual. Page 2-103 gives a full UDF listing of a degassing boundary condition.

Best,
ComputerGuy

Thank you very much, computerGuy. I will look at Fluent help for it.

kevinlipps · December 19, 2012, 15:05

Hi,

I'm also simulating a special type of bubble column...

but I have a problem now with the degassing UDF.

I managed to compile the UDF from the Fluent Tutorial, but I don't know what I have to do afterwards.

Could somebody plz explain how to use and setup the degassing UDF step by step? Maybe with a couple of screenshots, if its not too much trouble?

I know, that there is a degassing boundary in Fluent 14.5, but I dont have that version, so I have to stick with the self compiled UDF.

Thx in advance
Kevin

iitgbim · December 20, 2012, 08:33

Dear Kevin

Will you please share the compiled udf? I have not got any success in compiling this?

azna · November 23, 2015, 13:55

Hi,

I'm working on a bubble column. I was wondering that how can I modify settings in the degassing boundary condition ? close to the water surface, it under predicts velocity for both air and water. Is there any way that I can fix this problem near the water surface ? the flow pattern with degassing boundary is correct however, velocities near the water surface is very low comparing with experimental values.

Thanks a lot

December 20, 2011, 04:02	UDF for degassing boundary condition	#1
peaker007 New Member Join Date: Apr 2011 Posts: 9 Rep Power: 15	I am doing simulation about bubble column which gas goes in from the bottom but outflow from the top of reactor. I have read some papers who treated the outlet as a degassing boundary condition. It illustrated as follows: at the top of the reactor, an outlet boundary condition has been used for the gas phase and a symmetry boundary condition has been used for the liquid phase, this degassing condition has been implemented through a user defined function. I am not proficient about UDF, who can give me an example UDF for degassing boundary condition or give me some advice about how to write the UDF.Thank you very much for your kindness.

December 19, 2012, 15:05	Settings for degassing UDF?	#4
kevinlipps New Member Kevin Join Date: Mar 2012 Posts: 10 Rep Power: 14	Hi, I'm also simulating a special type of bubble column... but I have a problem now with the degassing UDF. I managed to compile the UDF from the Fluent Tutorial, but I don't know what I have to do afterwards. Could somebody plz explain how to use and setup the degassing UDF step by step? Maybe with a couple of screenshots, if its not too much trouble? I know, that there is a degassing boundary in Fluent 14.5, but I dont have that version, so I have to stick with the self compiled UDF. Thx in advance Kevin

November 23, 2015, 13:55	degassing boundary condition	#6
azna Member azna Join Date: Nov 2012 Posts: 30 Rep Power: 14	Hi, I'm working on a bubble column. I was wondering that how can I modify settings in the degassing boundary condition ? close to the water surface, it under predicts velocity for both air and water. Is there any way that I can fix this problem near the water surface ? the flow pattern with degassing boundary is correct however, velocities near the water surface is very low comparing with experimental values. Thanks a lot

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December 29, 2011, 19:47		#2
ComputerGuy Senior Member Real Name :) Join Date: Jan 2010 Location: United States Posts: 192 Rep Power: 16	Peaker007, Have a look at the Fluent 12 (or up?) UDF manual. Page 2-103 gives a full UDF listing of a degassing boundary condition. Best, ComputerGuy

December 20, 2012, 08:33		#5
iitgbim New Member Bimlesh Join Date: May 2012 Posts: 12 Rep Power: 14	Dear Kevin Will you please share the compiled udf? I have not got any success in compiling this?