CFD Online Logo CFD Online URL
www.cfd-online.com
[Sponsors]
Home > Forums > Software User Forums > ANSYS > FLUENT

behavior of two phase flow in a pipe

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

Reply
 
LinkBack Thread Tools Search this Thread Display Modes
Old   January 7, 2010, 13:54
Question behavior of two phase flow in a pipe
  #1
New Member
 
Sonia
Join Date: Dec 2009
Posts: 3
Rep Power: 16
Sonia84 is on a distinguished road
Hi,

Please,
Could you help me?
I try to modelise the behavior of two phase flow in a pipe. And I don't know how to do this correctly.
The issue is:
In a pipe (DN 100) flows a vapor with a given flowrate (different flowrates will have to simulate).
At a givent time t appears (this is not modelise) a volume of water (1 liter) (at t the volume is unity, like a slug) with a defined velocity different of the vapor one.
I would like modelize :
- the behavior of the two phase flow along the pipe
- the velocity of the water phase

Must I use the VOF model, in transient ....
thank you for your help,

Sonia
Sonia84 is offline   Reply With Quote

Old   January 8, 2010, 10:29
Default mp flow
  #2
Senior Member
 
CFDtoy
Join Date: Mar 2009
Location: United States
Posts: 145
Blog Entries: 2
Rep Power: 17
CFDtoy is on a distinguished road
Hi there,
Could you present a schematic for this process? if you want to capture the exact interface of liquid - air , you should go for VOF. If you want to simulate mixing and provided that the velocities of the phases are pretty close ..use mixture model, else, use Eulerian-eulerian formulation to model the two phase flow.

btw, If it is something like liquid and gas flowing in the same duct - separately and you wnt to capture wave effects on the interface etc..should go for VOF modeling.


Thanks,

CFDtoy
visit http://cfdtoy.blogspot.com


Quote:
Originally Posted by Sonia84 View Post
Hi,

Please,
Could you help me?
I try to modelise the behavior of two phase flow in a pipe. And I don't know how to do this correctly.
The issue is:
In a pipe (DN 100) flows a vapor with a given flowrate (different flowrates will have to simulate).
At a givent time t appears (this is not modelise) a volume of water (1 liter) (at t the volume is unity, like a slug) with a defined velocity different of the vapor one.
I would like modelize :
- the behavior of the two phase flow along the pipe
- the velocity of the water phase

Must I use the VOF model, in transient ....
thank you for your help,

Sonia
CFDtoy is offline   Reply With Quote

Old   January 9, 2010, 12:37
Default diphasique flow in horizontal pipe (mix and developemnt)
  #3
New Member
 
Sonia
Join Date: Dec 2009
Posts: 3
Rep Power: 16
Sonia84 is on a distinguished road
Hi,
thanks for your reply.

I attachment you could find a schema of my issue.
I want to capture the mix of the two flw and then the velocity of the phase ansd then the behavior of the flow (stratified, slug or droplets) in function of the distance foolowing the velocity of each phase.


thanks,

Sonia
Attached Images
File Type: jpg dphasique issue.JPG (16.6 KB, 115 views)
Sonia84 is offline   Reply With Quote

Old   January 9, 2010, 20:35
Default mixing problem
  #4
Senior Member
 
CFDtoy
Join Date: Mar 2009
Location: United States
Posts: 145
Blog Entries: 2
Rep Power: 17
CFDtoy is on a distinguished road
Hi there,
You should definitely consider using Eulerian-Eulerian scheme which will predict mixing of phases and + consider the velocity slip between phases. VOF scheme could work too - but when you impinge air and water, the initial level of disturbance can be captured only with very fine grids (drop formation etc) .Basic liquid slug flow with the droplet distribution (average distribution) can be figured using the Eulerian model.

with VOF it assumes the both the phases share the same velocity and mixed at the continuum level. Not sure if you want that.

But, if you want to predict droplets inside water or air bubbles in water to a fine level go for VOF.

The models are easy to set up and convergence for these problems can be achieved pretty well. So, may be you can try both methods and post results here.. Looks like a nice study for everyone to see which model gives the required result.

I have some information on VOF studies in my blog.

Let me know if you require any other information.

Thanks,

CFDtoy
Visit http://cfdtoy.blogspot.com




Quote:
Originally Posted by Sonia84 View Post
Hi,
thanks for your reply.

I attachment you could find a schema of my issue.
I want to capture the mix of the two flw and then the velocity of the phase ansd then the behavior of the flow (stratified, slug or droplets) in function of the distance foolowing the velocity of each phase.


thanks,

Sonia
CFDtoy is offline   Reply With Quote

Old   January 10, 2010, 19:05
Default work on mixing
  #5
Senior Member
 
CFDtoy
Join Date: Mar 2009
Location: United States
Posts: 145
Blog Entries: 2
Rep Power: 17
CFDtoy is on a distinguished road
Hi,
I came across this work on mixing / slug flow / droplet dynamics. Based on your flow profile VOF can be used. Take a look here

http://www.flow3d.com/pdfs/tp/micro_...i-Bib12-09.pdf


/CFDtoy
visit http://cfdtoy.blogspot.com

Quote:
Originally Posted by CFDtoy View Post
Hi there,
You should definitely consider using Eulerian-Eulerian scheme which will predict mixing of phases and + consider the velocity slip between phases. VOF scheme could work too - but when you impinge air and water, the initial level of disturbance can be captured only with very fine grids (drop formation etc) .Basic liquid slug flow with the droplet distribution (average distribution) can be figured using the Eulerian model.

with VOF it assumes the both the phases share the same velocity and mixed at the continuum level. Not sure if you want that.

But, if you want to predict droplets inside water or air bubbles in water to a fine level go for VOF.

The models are easy to set up and convergence for these problems can be achieved pretty well. So, may be you can try both methods and post results here.. Looks like a nice study for everyone to see which model gives the required result.

I have some information on VOF studies in my blog.

Let me know if you require any other information.

Thanks,

CFDtoy
Visit http://cfdtoy.blogspot.com
CFDtoy is offline   Reply With Quote

Old   September 17, 2013, 17:31
Default
  #6
New Member
 
Ahmad
Join Date: Aug 2013
Posts: 7
Rep Power: 13
ahmad786 is on a distinguished road
Quote:
Originally Posted by CFDtoy View Post
Hi,
I came across this work on mixing / slug flow / droplet dynamics. Based on your flow profile VOF can be used. Take a look here

http://www.flow3d.com/pdfs/tp/micro_...i-Bib12-09.pdf


/CFDtoy
visit http://cfdtoy.blogspot.com



CFD toy,
Hi CFD TOY.I am facing a hell of problems in simulating a flow in a steam turbine.The conditions for steam are:
1)-Dry saturated at inlet (P=5bar) of turbine with quality of "1"
Conditions of steam at the exit of turbine are :
2)-wet steam (P=1bar) with quality of "0.91"
Can u help me which model in CFX will be best in my case;
Secondly I am facing problems in assigning flow materials in CFX.
Currently I am using
"steam5vl" IAPWS -f97 libray as fluid material for my case.Is it right??
Should I use two materials steam gas and steam liquid from IAPWS library independently ??.Should I use homogeneous model or not?? Plz help me how should i assign flow materials for my case?? PLZ.
ahmad786 is offline   Reply With Quote

Reply

Tags
two-phase flow, vof

Thread Tools Search this Thread
Search this Thread:

Advanced Search
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 Off
Pingbacks are On
Refbacks are On


Similar Threads
Thread Thread Starter Forum Replies Last Post
pulsating static pressure around zero at pipe flow David Kim FLUENT 0 May 16, 2006 14:47
flow in pipe with momentum and energy source Atit Koonsrisuk CFX 3 March 29, 2005 17:58
outlet boudary condition for a flow in the pipe Atit CFX 2 November 9, 2004 18:43
gas solid pipe flow tahar Phoenics 6 November 3, 2003 13:03
compressible two phase flow in CFX4.4 youngan CFX 0 July 2, 2003 00:32


All times are GMT -4. The time now is 11:00.