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

interpolation strategy for topological change

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

Reply
 
LinkBack Thread Tools Display Modes
Old   February 8, 2016, 05:29
Default interpolation strategy for topological change
  #1
New Member
 
Join Date: Oct 2014
Posts: 21
Rep Power: 4
DrFloyd is on a distinguished road
Hi everyone,

I studied several cases with rhoPimpleDymFoam about topological changes of mesh (topoChangerFvMesh), and now i'm trying to understand wich strategy is used by default to initialize new cell layers added. In other words, in my case i have a cylinder with a moving boundary (piston), and according with piston movement a new cell layer is added or removed. That's ok. Now I would like to know how the new cells added are initilized in relation with their velocity, pressure, temperature...
Thanks for your help.

Last edited by DrFloyd; February 9, 2016 at 08:21.
DrFloyd is offline   Reply With Quote

Old   February 11, 2016, 09:23
Default interpolation strategy for topological change
  #2
New Member
 
Join Date: Oct 2014
Posts: 21
Rep Power: 4
DrFloyd is on a distinguished road
no one has an idea or suggestion?
DrFloyd is offline   Reply With Quote

Old   February 11, 2016, 14:19
Default
  #3
Senior Member
 
Sandeep Menon
Join Date: Mar 2009
Location: Amherst, MA
Posts: 390
Rep Power: 16
deepsterblue will become famous soon enough
For layer addition, cells / faces are inflated from zero cell-volume / face-area. As a result, it doesn't matter what value is assigned to the new cell, because at the old-time, the volume was zero (and so, solver quantities are multiplied with zeros at the old-time) and the faces are swept to a non-zero cell-volume at the new-time level.

Hope this helps.
__________________
Sandeep Menon
University of Massachusetts Amherst
https://github.com/smenon
deepsterblue is offline   Reply With Quote

Old   February 12, 2016, 06:14
Default
  #4
New Member
 
Join Date: Oct 2014
Posts: 21
Rep Power: 4
DrFloyd is on a distinguished road
Thankyou very much for your help Sandeep.

I'm not sure I understood your answer. I explain my interpretation.
I have a piston going down and a new cell layer is added. I'm using the PISO algorithm and at new timestep I have two new situations:
1) deforming grid;
2) the deformed grid is "cutted" by a plane that generates new cell layer;
I'm using PISO algorithm and I have to initialize all new cells with non-zero volume. How OF initializes these new cell?
I think possibilities are two:
1) It initializes with zero value for T, p, v... and It lets the algorithm to update these values
2) It initializes these values with a linear interpolation from old-cell and at old-time step to the new cell position... and It lets the algorithm to update these values

I attached an image to explain better the situation.

Thanks again!
Attached Images
File Type: jpeg jpg.jpeg (41.5 KB, 17 views)

Last edited by DrFloyd; February 22, 2016 at 05:05.
DrFloyd 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
Mass Transfer without Phase Change in InterPhaseChangeFoam Parisa_Khiabani OpenFOAM Running, Solving & CFD 5 May 26, 2015 09:40
Help with writing a macro/UDF_file/script to change BC at regular time step intervals Codophobia Fluent Multiphase 0 April 24, 2014 10:07
log-law change - Fluent C.C FLUENT 1 November 5, 2012 10:25
How to change molecular weight of a species in pdf-mixture Jenny_W FLUENT 0 November 3, 2012 17:49
Sudden pressure change in overset Ben Main CFD Forum 6 July 21, 2007 19:46


All times are GMT -4. The time now is 01:40.