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

Mesh discontinuity

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

Reply
 
LinkBack Thread Tools Search this Thread Display Modes
Old   March 23, 2017, 07:49
Exclamation Mesh discontinuity
  #1
New Member
 
John,Lu
Join Date: Jul 2015
Posts: 10
Rep Power: 8
hippo407 is on a distinguished road
Dear every cfx experts.
I have a question about different bodys to form an another part.
By my opinion, this is one way can make all mesh points merge together in the interface between each bodys. but my question is , in some complicate CAD case even a part contain many parts , it is still happen the nodes are not match together.

Is there any way to find and check which interface is not matching together or any way can make 100% the interface mesh be matched?

I know can set interface to use ggi match different mesh face by users . But I still curious about this situation whether have more convenient way to resolve .
hippo407 is offline   Reply With Quote

Old   March 23, 2017, 18:23
Default
  #2
Super Moderator
 
Glenn Horrocks
Join Date: Mar 2009
Location: Sydney, Australia
Posts: 16,877
Rep Power: 132
ghorrocks is just really niceghorrocks is just really niceghorrocks is just really niceghorrocks is just really nice
Have a look at the overlap % in the output file and in CFD-Post in the results file.
ghorrocks is offline   Reply With Quote

Old   March 23, 2017, 22:24
Default
  #3
New Member
 
John,Lu
Join Date: Jul 2015
Posts: 10
Rep Power: 8
hippo407 is on a distinguished road
thank you for reply,Glenn

Can the overlap % you mentioned be used to check the interface inside a part which contain many bodys but mesh may not connect like hex with tetra and said bodys are full in the same domain?
hippo407 is offline   Reply With Quote

Old   March 23, 2017, 22:38
Default
  #4
Super Moderator
 
Glenn Horrocks
Join Date: Mar 2009
Location: Sydney, Australia
Posts: 16,877
Rep Power: 132
ghorrocks is just really niceghorrocks is just really niceghorrocks is just really niceghorrocks is just really nice
The overlap % simply returns the % of the area of one side of the GGI which it has managed to find the matching face on the other side of the GGI. Whether the sides are in different domains or not, tet or hex mesh or anything like that does not matter.
ghorrocks is offline   Reply With Quote

Old   March 23, 2017, 22:54
Default
  #5
New Member
 
John,Lu
Join Date: Jul 2015
Posts: 10
Rep Power: 8
hippo407 is on a distinguished road
Actually, I may not describe very clear.
my case is a part contain many bodies (already form a new part in geometry) and only one body use subdomain to get energy source , and all bodies are in the same domain. When I finish the simulation , I find the temperature distribution is very strange and I guess the interface between the subdomain one and other nearby bodies many not correct connect .

So I operate an easier model to test , I find if the meshes of said all bodies inside are connected ,it is not necessary to set interface in one domain , default setting is fine ,but if mesh are discontinued since node not math or using differ mesh method on different body (hex with tet),the interface inside will not exchange the heat.

So my confusion is , Is there any way to check all mesh of a part contains many bodies really connected between every bodies inside a part ? or just to see by eyes and set interface even in the same doman and same part.

thanks!
hippo407 is offline   Reply With Quote

Old   March 24, 2017, 01:45
Default
  #6
Super Moderator
 
Glenn Horrocks
Join Date: Mar 2009
Location: Sydney, Australia
Posts: 16,877
Rep Power: 132
ghorrocks is just really niceghorrocks is just really niceghorrocks is just really niceghorrocks is just really nice
Have a look at the non-overlap fraction in CFD-Post to see where your interface connects and where it does not.
ghorrocks is offline   Reply With Quote

Old   March 24, 2017, 02:07
Default
  #7
New Member
 
John,Lu
Join Date: Jul 2015
Posts: 10
Rep Power: 8
hippo407 is on a distinguished road
Yes , I got i . thank you Glenn for reply it , so in some complicate CAD, even bodies are in one part maybe need to set interface manually or just improving the mesh. I appriciate it!!

Otherwise, I see ANSYS HELP under the title "Non-overlap Boundary Conditions" mention that "Nonoverlap Fraction or (1-Nonoverlap Fraction) to ignore contributions from nodes on a GGI interface" I am confused about what is used for . like to set the heat flux turn to 0 ?
hippo407 is offline   Reply With Quote

Old   March 24, 2017, 07:16
Default
  #8
Super Moderator
 
Glenn Horrocks
Join Date: Mar 2009
Location: Sydney, Australia
Posts: 16,877
Rep Power: 132
ghorrocks is just really niceghorrocks is just really niceghorrocks is just really niceghorrocks is just really nice
I do not know the reference you are talking about. What section of the documentation is that from?
ghorrocks is offline   Reply With Quote

Old   March 26, 2017, 11:34
Default
  #9
New Member
 
John,Lu
Join Date: Jul 2015
Posts: 10
Rep Power: 8
hippo407 is on a distinguished road
hey , my ref comes from here.
could you help me to have a look?

it located on the last sentence under 5.4.3.1

https://www.sharcnet.ca/Software/Ans.../CACBCJBF.html
hippo407 is offline   Reply With Quote

Old   March 26, 2017, 21:44
Default
  #10
Super Moderator
 
Glenn Horrocks
Join Date: Mar 2009
Location: Sydney, Australia
Posts: 16,877
Rep Power: 132
ghorrocks is just really niceghorrocks is just really niceghorrocks is just really niceghorrocks is just really nice
If you read the full sentence it is quite clear to me:

Quote:
For example, you could multiply a quantity in an expression by Nonoverlap Fraction or (1-Nonoverlap Fraction) to ignore contributions from nodes on a GGI interface that are in the overlap portion, or non-overlap portion, respectively
ghorrocks is offline   Reply With Quote

Old   March 27, 2017, 00:14
Default
  #11
New Member
 
John,Lu
Join Date: Jul 2015
Posts: 10
Rep Power: 8
hippo407 is on a distinguished road
Is it used on the source term and make the flux crossing the interface can be zero or anything?

could you show me a simple example ? I am very appreciated
hippo407 is offline   Reply With Quote

Old   March 27, 2017, 08:11
Default
  #12
Super Moderator
 
Glenn Horrocks
Join Date: Mar 2009
Location: Sydney, Australia
Posts: 16,877
Rep Power: 132
ghorrocks is just really niceghorrocks is just really niceghorrocks is just really niceghorrocks is just really nice
You simply put the Nonoverlap Fraction variable in the CEL expression to evaluate the source term. But before we talk about the details of this - what are you trying to?
ghorrocks is offline   Reply With Quote

Old   March 27, 2017, 22:27
Default
  #13
New Member
 
John,Lu
Join Date: Jul 2015
Posts: 10
Rep Power: 8
hippo407 is on a distinguished road
For my project , I am trying using auto generation for the interfaces, and I want to know whether this function is complete or not.By my test, I think it is powerful enough and only need to check the nonoverlap fraction as you said in the CFD post and find anywhere need to be set interface manually.

And the last question is just my curious problem which I saw at the help.

If there is any misunderstand concept ,plz tell me. thanks
hippo407 is offline   Reply With Quote

Reply

Tags
interface, mesh

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
sliding mesh problem in CFX Saima CFX 46 September 11, 2021 08:38
decomposePar problem: Cell 0contains face labels out of range vaina74 OpenFOAM Pre-Processing 37 July 20, 2020 06:38
[snappyHexMesh] Multi Region Mesh of a car filter Zephiro88 OpenFOAM Meshing & Mesh Conversion 3 September 11, 2019 20:34
[ICEM] Problem making structural mesh on a surface froztbear ANSYS Meshing & Geometry 1 November 10, 2011 09:52
engrid -> save as .stl with boundarie codes Zymon enGrid 31 August 29, 2011 14:40


All times are GMT -4. The time now is 02:49.