CFD Online Logo CFD Online URL
www.cfd-online.com
[Sponsors]
Home > Forums > CFX

Multiphase region definition problem

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

Reply
 
LinkBack Thread Tools Display Modes
Old   August 15, 2010, 03:40
Default Multiphase region definition problem
  #1
New Member
 
Shahed
Join Date: Aug 2010
Posts: 4
Rep Power: 6
Shahed is on a distinguished road
Hi everyone, i'm new to this board...

the simulation is a simple falling water in a tank under gravity force...

the geometry is a simple rectangular with two regions (it's a 2D mesh)... one on top, which is smaller and it's going to be defined as water. and the rest of the face is air. i want to simulate a transient flow for seeing how water actually falls down...

i define each domain in Basic Settings separately (the top region, Water and the bottom region, Air) but when I check it again, i surprisingly face that two regions are in the same phase!!

the question is how can i apply these settings to be sure that my each domains are in the specified phase that i want?...

it's part of my final project and i really need this help. i hope someone can give me the right direction.

Regards,
Shahed
Attached Images
File Type: jpg untitled2.JPG (73.6 KB, 16 views)
Shahed is offline   Reply With Quote

Old   August 15, 2010, 06:47
Default
  #2
Super Moderator
 
Glenn Horrocks
Join Date: Mar 2009
Location: Sydney, Australia
Posts: 10,800
Rep Power: 85
ghorrocks has a spectacular aura aboutghorrocks has a spectacular aura aboutghorrocks has a spectacular aura about
Don't define the top region as a different domain. Make the entire thing one domain and use a function to define the air/water initial condition. A function setting the water volume fraction to something like step((z-height)/1[m]) will do it.

Also this flow is bound to be three dimensional. Your 2D results are going to be totally wrong. If you are just doing it to start off that is fine to get the simulation going, but be aware that for an accurate result it is going to be 3D.
ghorrocks is offline   Reply With Quote

Old   August 15, 2010, 07:01
Default
  #3
New Member
 
Shahed
Join Date: Aug 2010
Posts: 4
Rep Power: 6
Shahed is on a distinguished road
thanks for the note. yes it's just a beginning for the case i'm studying...

but can you explain more specifically about the whole function thing? i haven't seen such menu's in CFX...

very appreciated
Shahed is offline   Reply With Quote

Old   August 15, 2010, 07:11
Default
  #4
Super Moderator
 
Glenn Horrocks
Join Date: Mar 2009
Location: Sydney, Australia
Posts: 10,800
Rep Power: 85
ghorrocks has a spectacular aura aboutghorrocks has a spectacular aura aboutghorrocks has a spectacular aura about
Have a look at the flow over a bump tutorial which gets installed with CFX. It is all one domain and an expression to set the air/water initial condition.
ghorrocks is offline   Reply With Quote

Old   August 15, 2010, 07:50
Default
  #5
New Member
 
Shahed
Join Date: Aug 2010
Posts: 4
Rep Power: 6
Shahed is on a distinguished road
can you tell the exact name please, i can't find it. apparently the only multiphase flow in Ansys, CFX 12 is "Multiphase Flow in a Mixing Vessel"...

my final approach is to simulate a heat pipe by CFX... i've designed and almost constructed a heat pipe with all the details (heat-exchanger, a PCB for reading temperatures, etc... )

can i have your e-mail?
it would be great if i can use your advice
Shahed is offline   Reply With Quote

Old   August 15, 2010, 19:00
Default
  #6
Super Moderator
 
Glenn Horrocks
Join Date: Mar 2009
Location: Sydney, Australia
Posts: 10,800
Rep Power: 85
ghorrocks has a spectacular aura aboutghorrocks has a spectacular aura aboutghorrocks has a spectacular aura about
Have a look in the CFX documentation to find it. You will find the files for it in <CFX_ROOT>/examples.

Sorry, I don't give out my email address on the forum. If you have a question post it on the forum then you can get many people to help answer it. And only private message me if you actually have a private message for me - if it is a general question it should be posted on the forum.
ghorrocks is offline   Reply With Quote

Old   August 16, 2010, 03:33
Default
  #7
New Member
 
Shahed
Join Date: Aug 2010
Posts: 4
Rep Power: 6
Shahed is on a distinguished road
yeah, i found it. it's Free Surface Flow Over a Bump
.....
fair enough pal, i will post my questions here... Thank you
Shahed is offline   Reply With Quote

Reply

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


Similar Threads
Thread Thread Starter Forum Replies Last Post
Suggestions for a multi region conjugate heat transfer problem maddalena OpenFOAM 14 September 4, 2013 18:03
mass balance problem in multiphase model mdsanij1 FLUENT 0 July 28, 2009 16:01
UDF problem in multiphase model Amir Khodabandeh FLUENT 1 March 13, 2009 09:43
Is it multiphase problem? Se-Hee CFX 1 November 4, 2006 05:25
problem with MFR model for multiphase mixing tanks Srinivas Main CFD Forum 1 November 7, 2005 15:16


All times are GMT -4. The time now is 02:12.