problem with inlet BC setting

Tanjina · June 13, 2013, 12:31

Hi all.
Currently I am working on a simple geometry with fluent where water will enter from static reservoir into pipe and air will replace the empty place of reservoir. I put pressure inlet. But it didn't give this type of result. Water is coming instead of air. Could anyone suggest me how can I set inlet BC for this type of phenomena?

I tried to put "air", "water" and "mixture" in pressure inlet ( I also tried with velocity inlet), but fluent says "this type of setting is not application for current setting" for air.

oj.bulmer · June 14, 2013, 11:33

This is a classic case of VOF model. Have a look at tank flushing tutorial:
http://www.youtube.com/watch?v=xJs0NVivIYk

You need a clear interface between air and water, and Eulerian models (which I suspct you tried) are not suitable for this.

OJ

Tanjina · June 14, 2013, 12:06

Thanks for your reply. I have used VOF model for this. Can't set the inlet properly. Last night I tried with volume fraction of water liquid in inlet 0.5. After 500 run, result is look like the attached image.

hossein65 · June 30, 2013, 19:32

you have to patch the water on your reservoir
your problem is transient, so, don't use steady solver
pressure inlet seems OK, but the major issue is that you have to make sure there is no water in your pressure inlet as you want to make the reservoir empty

Tanjina · July 1, 2013, 14:06

Thanks a lot Hossein. Finally I have solved my this BC problem some days ago and model is given the expected results. I already did exactly what you said in this thread.

Now I am trying to set up an different model. And facing problem with geometry. Should I discuss about it i this thread, or will I start a new thread ? Please let me know.

June 30, 2013, 19:32		#4
hossein65 Member Hossein Join Date: Oct 2010 Location: Greensboro, NC, USA Posts: 30 Rep Power: 16	you have to patch the water on your reservoir your problem is transient, so, don't use steady solver pressure inlet seems OK, but the major issue is that you have to make sure there is no water in your pressure inlet as you want to make the reservoir empty __________________ Hossein Amini PhD student in Biochemical Engineering; Computational Science and Engineering department; North Carolina Agricultural and Technical State University

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June 14, 2013, 11:33		#2
oj.bulmer Senior Member OJ Join Date: Apr 2012 Location: United Kindom Posts: 473 Rep Power: 20	This is a classic case of VOF model. Have a look at tank flushing tutorial: http://www.youtube.com/watch?v=xJs0NVivIYk You need a clear interface between air and water, and Eulerian models (which I suspct you tried) are not suitable for this. OJ

July 1, 2013, 14:06		#5
Tanjina Senior Member Tanjina Afrin Join Date: May 2013 Location: South Carolina Posts: 169 Rep Power: 13	Thanks a lot Hossein. Finally I have solved my this BC problem some days ago and model is given the expected results. I already did exactly what you said in this thread. Now I am trying to set up an different model. And facing problem with geometry. Should I discuss about it i this thread, or will I start a new thread ? Please let me know.