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

Assigning anisotropic permeability in ANSYS CFX

Register Blogs Community New Posts Updated Threads Search

Like Tree1Likes
  • 1 Post By ghorrocks

Reply
 
LinkBack Thread Tools Search this Thread Display Modes
Old   September 9, 2016, 05:21
Default Assigning anisotropic permeability in ANSYS CFX
  #1
New Member
 
willsen
Join Date: Sep 2016
Posts: 11
Rep Power: 10
willsen is on a distinguished road
Hi Everyone!

I am trying to model resin flow through a textile unit cell as can be referred to the attached picture. From the picture it is clear that the fluid will flow at inter-tow channel (the gap BETWEEN the fibrous yarns). Furthermore there will also be flow inside the yarns (because each yarn consists of thousands of fibers).

To model the flow through this unit cell two domains shall be defined: fluid domain (inter-tow channel) and porous domain (the tows).

My question is, is it possible to assign permeability tensor in ANSYS CFX? Furthermore, is there a trick to transform this permeability tensor according the direction of the tow?

Thank you very much!
Attached Images
File Type: jpg diamond.jpg (42.3 KB, 14 views)
willsen is offline   Reply With Quote

Old   September 9, 2016, 08:17
Default
  #2
Super Moderator
 
Glenn Horrocks
Join Date: Mar 2009
Location: Sydney, Australia
Posts: 17,844
Rep Power: 144
ghorrocks is just really niceghorrocks is just really niceghorrocks is just really niceghorrocks is just really nice
Sounds like you need the directional loss porous model. Have a look in the documentation for details.
ghorrocks is offline   Reply With Quote

Old   September 9, 2016, 22:11
Default
  #3
New Member
 
willsen
Join Date: Sep 2016
Posts: 11
Rep Power: 10
willsen is on a distinguished road
Hi,

Thank you very much for your kind reply. Are you referring to the 3 types of momentum sources (isotropic loss model, directional loss model, and general momentum sources)?
willsen is offline   Reply With Quote

Old   September 9, 2016, 22:37
Default
  #4
Super Moderator
 
Glenn Horrocks
Join Date: Mar 2009
Location: Sydney, Australia
Posts: 17,844
Rep Power: 144
ghorrocks is just really niceghorrocks is just really niceghorrocks is just really niceghorrocks is just really nice
Yes, that is correct.

Or are you talking about the area porosity tensor? To quote from the documentation: "ANSYS CFX presently allows only K to be isotropic". So you cannot use an anisotropic area porosity tensor.

So you can specify the resistance to be in any direction you like, but the area porosity tensor must be isotropic.

There may be beta features to get around this. I am not familiar with them so cannot help you there. Others on the forum may be, or you can ask ANSYS support.
ghorrocks is offline   Reply With Quote

Old   September 9, 2016, 23:06
Default
  #5
New Member
 
willsen
Join Date: Sep 2016
Posts: 11
Rep Power: 10
willsen is on a distinguished road
Hi,

Once again thank you for your reply. So the way I would like to approach this is by first determining the permeability tensor inside the tows through an analytical model (which I have already calculated from the information of the porosity inside the tows and the fibre radius).

To model the flow inside the tows, I would like to input this permeability tensor inside the yarn accordingly depending on the principal direction of the tows and obtain the velocity inside the tows in term of superficial velocity. So I don't really need to input this porosity information as it has already been taken into account when I calculated the tows' permeability analytically.

To my understanding, ANSYS CFX allows me to obtain this superficial velocity field inside the tows by simply adding momentum loss term to the governing flow equation (without altering the equations like in the full porous model). According to the documentation (I screenshot the relevant section from Solver Theory Guide), this is done by defining the porous body as FLUID DOMAIN. However, ANSYS CFX only allows me to add these directional porous losses terms in the POROUS DOMAIN under the porosity setting tab. Do you think there is a miscommunication from the documentation?

Furthermore, the momentum loss term requires both PERMEABILITY and QUADRATIC LOSS COEFFICIENT. How do we calculate this quadratic loss coefficient? I have never come across any literature in the field of textile permeability that includes this quadratic loss coefficient in their numerical model.

THANK YOU. Really in desperate need for advice.
Attached Images
File Type: jpg documentation.jpg (110.1 KB, 12 views)
willsen is offline   Reply With Quote

Old   September 10, 2016, 08:58
Default
  #6
Super Moderator
 
Glenn Horrocks
Join Date: Mar 2009
Location: Sydney, Australia
Posts: 17,844
Rep Power: 144
ghorrocks is just really niceghorrocks is just really niceghorrocks is just really niceghorrocks is just really nice
I am not an expert on porous models in CFX. Hopefully others in the forum can answer you question.
willsen likes this.
ghorrocks is offline   Reply With Quote

Old   September 10, 2016, 18:40
Default
  #7
New Member
 
willsen
Join Date: Sep 2016
Posts: 11
Rep Power: 10
willsen is on a distinguished road
Thank you very much for your help. I shall report my question to the forum so that other people in the forum don't think that the problem has been resolved. Appreciate your help once again
willsen is offline   Reply With Quote

Reply

Tags
anisotropic, permeability


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
Compressible Flow in Ansys CFX bcheruk CFX 15 July 6, 2017 07:30
Calculation of the Governing Equations Mihail CFX 7 September 7, 2014 07:27
Orthotropic Properties in ANSYS CFX 14.5 (XY, YZ, XZ) lmark84l CFX 2 August 6, 2014 12:34
ANSYS CFX Tutorial Rashid CFX 25 December 20, 2012 02:22
Ansys 13 CFX problem on LInux Opensuse 11.4 serendipity CFX 10 August 7, 2012 04:24


All times are GMT -4. The time now is 23:32.