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-   -   Boundary conditions for 2phase countercurrent flow (http://www.cfd-online.com/Forums/fluent/32739-boundary-conditions-2phase-countercurrent-flow.html)

 rakib December 18, 2003 11:19

Boundary conditions for 2phase countercurrent flow

Hello,

For countercurrent gas liquid flow in a packed column, how are the inlet boundary conditions to be defined? The top liquid inlet is also supposed to be outlet for the gas (gas will be bubbling out through the liquid surface) and at the same time, the gas inlet at the bottom is supposed to be liquid drain out area. Or is it that in the top and bottom plates, holes have to be defined separately as inlets and the rest as outlets.

 thomas December 18, 2003 18:21

Re: Boundary conditions for 2phase countercurrent

Hi, I think you have to define via a UDF what you want to go in and out of your column.

thomas

 rakib December 19, 2003 03:18

Re: Boundary conditions for 2phase countercurrent

Means the same top plate can be defined as inlet for the liquid distribution, and also as outlet for the gas by using a UDF? Is there any sample UDF available so that I can get some idea? Thanks, rakib

 thomas December 19, 2003 06:30

Re: Boundary conditions for 2phase countercurrent

Hi, Contact your nearest fluent office, they might have something like that in their data base, if not they'll guide you. I have not treated this problem yet, but in my opinion I would try to define the oulet and inlet of your column as a velocity inlet and hook up a UDF over it. In that UDF you could use a DEFINE_PROFILE to define what goes in & out at both inlet and outlet face. For example, supposing your column is contercurrent gas/liquid contactor. Indeed the gas is injected from the bottom and liquid from the top. Lets take the inlet (=column bottom). A simple velocity inlet will make your gas get in but will make also your liquid recirculated instead of leaving the column. There, declare a DEFINE_PROFILE which prevents the liquid recirculation at the inlet (i.e: impose at the inlet face the axial water velocity of the first range of cell after the inlet. Like that your water will leave the domain at the column bottom). For the outlet I would personnaly do quasi the same thing and use a velocity inlet.

Hope this help & Let me know how that goes pls !

Merry chrismas and happy new year, thomas

 fcabrales April 11, 2011 20:58

were you guys able to set up the boundary conditions for your simulation? I am having the same problem as your.