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

Shear stress in perforated pipe for horizontal wells

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

Reply
 
LinkBack Thread Tools Display Modes
Old   October 12, 2012, 17:24
Default Shear stress in perforated pipe for horizontal wells
  #1
New Member
 
Mohammed
Join Date: Oct 2012
Posts: 27
Rep Power: 4
mohw2002 is on a distinguished road
I am working on the wellbore (perforated pipe) for horizontal wells. I want to calculate the shear stress tau w and friction factor f from CFX.
mohw2002 is offline   Reply With Quote

Old   October 13, 2012, 03:27
Default
  #2
Senior Member
 
S.Bogoda
Join Date: Jul 2012
Posts: 133
Rep Power: 5
sakurabogoda is on a distinguished road
As far as I know, it is not easy to find friction factor by CFX as when you model it you should input stream-wise and transverse loss coefficients. Without knowing them you cannot model it. So better to do a simulation or get experimental data.
Pls. this is according to my knowledge and experiences.
sakurabogoda is offline   Reply With Quote

Old   October 13, 2012, 05:32
Default
  #3
Super Moderator
 
Glenn Horrocks
Join Date: Mar 2009
Location: Sydney, Australia
Posts: 10,821
Rep Power: 85
ghorrocks has a spectacular aura aboutghorrocks has a spectacular aura aboutghorrocks has a spectacular aura about
What friction factor are you looking for? There are many definitions of it.

Wall shear stress is easy to extract - is this what you mean by shear stress tau w?
ghorrocks is online now   Reply With Quote

Old   October 13, 2012, 10:28
Default
  #4
New Member
 
Mohammed
Join Date: Oct 2012
Posts: 27
Rep Power: 4
mohw2002 is on a distinguished road
Hi ghorrocks.
I mean how can I calculate the shear stress inside the pipe wall due pressure drop due to wall friction and then calculate friction factor f for turbulent flow. I am using CFX k-epsilon model.

Regards.
mohw2002 is offline   Reply With Quote

Old   October 13, 2012, 10:31
Default
  #5
New Member
 
Mohammed
Join Date: Oct 2012
Posts: 27
Rep Power: 4
mohw2002 is on a distinguished road
Hi Sakurabogoda.
How can I input stream-wise and transverse loss coefficients.

Regards.
mohw2002 is offline   Reply With Quote

Old   October 14, 2012, 04:13
Default
  #6
Super Moderator
 
Glenn Horrocks
Join Date: Mar 2009
Location: Sydney, Australia
Posts: 10,821
Rep Power: 85
ghorrocks has a spectacular aura aboutghorrocks has a spectacular aura aboutghorrocks has a spectacular aura about
Getting the wall shear stress is simple, it is a variable in the results file by default. Then you just need to get an average of it at the representative point along the length, and you can get the pressure drop from that. This is all pretty standard post-processing.

Sorry, what is stream wise and transverse loss coefficients? How are you defining these terms?
ghorrocks is online now   Reply With Quote

Old   October 15, 2012, 00:54
Default
  #7
Senior Member
 
S.Bogoda
Join Date: Jul 2012
Posts: 133
Rep Power: 5
sakurabogoda is on a distinguished road
When you do a porous or perforated design, you have to input directional losses; streamwise and transverse. Both are related to pressure drop and transverse loss can be take in terms of Streamwise coefficient. That is why I told to do simulation or experiment, to get pressure drop.

Dear Glenn,
I am doubt about how to get pressure drop by CFX without knowing directional losses. I would really appreciate your advice.
sakurabogoda is offline   Reply With Quote

Old   October 15, 2012, 02:52
Default
  #8
New Member
 
Mohammed
Join Date: Oct 2012
Posts: 27
Rep Power: 4
mohw2002 is on a distinguished road
Quote:
Originally Posted by sakurabogoda View Post
When you do a porous or perforated design, you have to input directional losses; streamwise and transverse. Both are related to pressure drop and transverse loss can be take in terms of Streamwise coefficient. That is why I told to do simulation or experiment, to get pressure drop.

Dear Glenn,
I am doubt about how to get pressure drop by CFX without knowing directional losses. I would really appreciate your advice.
Dear sakura
Sorry how can I do to input directional losses; streamwise and trasverse by CFX? I mean where? do you have toturial about this?
mohw2002 is offline   Reply With Quote

Old   October 15, 2012, 04:20
Default
  #9
Senior Member
 
S.Bogoda
Join Date: Jul 2012
Posts: 133
Rep Power: 5
sakurabogoda is on a distinguished road
Dear Mohammed,
Refer "Flow in a Catalytic Converter" in tutorial manual. It is about a porous domain, but you can get an idea how to modify it into your model.
sakurabogoda is offline   Reply With Quote

Old   October 15, 2012, 05:22
Default
  #10
Super Moderator
 
Glenn Horrocks
Join Date: Mar 2009
Location: Sydney, Australia
Posts: 10,821
Rep Power: 85
ghorrocks has a spectacular aura aboutghorrocks has a spectacular aura aboutghorrocks has a spectacular aura about
Assuming you have a normal fluid domain (not a porous domain) then can't you simply put a series of points (or maybe a line) along the centre line of the pipe and monitor points at the periphery? Then your streamwise loss coefficient can be calculated from the pressure drop along the pipe, and the transverse loss can be calculated from the pressure drop from inside the pipe to outside?

This is just straight forward post-processing.
ghorrocks is online now   Reply With Quote

Old   October 19, 2012, 16:58
Default
  #11
New Member
 
Mohammed
Join Date: Oct 2012
Posts: 27
Rep Power: 4
mohw2002 is on a distinguished road
Quote:
Originally Posted by ghorrocks View Post
Assuming you have a normal fluid domain (not a porous domain) then can't you simply put a series of points (or maybe a line) along the centre line of the pipe and monitor points at the periphery? Then your streamwise loss coefficient can be calculated from the pressure drop along the pipe, and the transverse loss can be calculated from the pressure drop from inside the pipe to outside?

This is just straight forward post-processing.
Hi
How can I do it at the post-processing without fix it at pre-processing?
mohw2002 is offline   Reply With Quote

Old   October 19, 2012, 17:06
Default
  #12
New Member
 
Mohammed
Join Date: Oct 2012
Posts: 27
Rep Power: 4
mohw2002 is on a distinguished road
Quote:
Originally Posted by sakurabogoda View Post
Dear Mohammed,
Refer "Flow in a Catalytic Converter" in tutorial manual. It is about a porous domain, but you can get an idea how to modify it into your model.
Dear
When I consider my geometry (perforated pipe) as a Catalytic Converter I have some questions
1- There is domain named (Subtarte) but how can I put in my model like that.
2- How much the value of volume porosity?
3- Set streamwise loss which one I will choose?
4- Can I use the Quadratic Resistance coefficient or another one?
5- How much value use to the streamwise coefficient Multiplier?
thanks
mohw2002 is offline   Reply With Quote

Old   October 20, 2012, 05:20
Default
  #13
Super Moderator
 
Glenn Horrocks
Join Date: Mar 2009
Location: Sydney, Australia
Posts: 10,821
Rep Power: 85
ghorrocks has a spectacular aura aboutghorrocks has a spectacular aura aboutghorrocks has a spectacular aura about
Quote:
How can I do it at the post-processing without fix it at pre-processing?
This is basic post-processing. Have you done the CFX tutorials? They describe how to post process your results. Likewise your reply to Mohammed is basic CFD which is covered in the tutorials.
ghorrocks is online now   Reply With Quote

Old   October 21, 2012, 21:16
Default
  #14
Senior Member
 
S.Bogoda
Join Date: Jul 2012
Posts: 133
Rep Power: 5
sakurabogoda is on a distinguished road
Dear Mohammed,
All parameters depend on your design. Read CFX theory guide and there it specified how to create the domain and loss model, with/without the effect of volume porosity.
Other setting has to be define by you. You should have a stramwise loss due to the wall shear.
sakurabogoda 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
Measuring wall shear stress in bend pipe liguifan OpenFOAM 69 September 13, 2014 08:55
Wall Shear Stress in a Pipe itsme_kit CD-adapco 4 February 11, 2012 13:32
shear stress scalar definitions? Novak Elliott CFX 0 April 6, 2003 01:45
Terrible Mistake In Fluid Dynamics History Abhi Main CFD Forum 12 July 8, 2002 09:11
What is the detail definition of wall shear stress zjm FLUENT 0 January 2, 2002 08:43


All times are GMT -4. The time now is 05:46.