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

append-mesh-data memory leak?

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

Like Tree1Likes
  • 1 Post By LuckyTran

Reply
 
LinkBack Thread Tools Display Modes
Old   June 5, 2017, 18:19
Default append-mesh-data memory leak?
  #1
Senior Member
 
Lucky Tran
Join Date: Apr 2011
Location: Orlando, FL USA
Posts: 1,821
Rep Power: 26
LuckyTran will become famous soon enoughLuckyTran will become famous soon enough
I've had this issue in Fluent v17 & v18. My guess is, it can happen in any version of Fluent. Does anyone know a workaround?

I'm running LES on a pipe flow and want to double the length of my pipe by appending the case-data.

/mesh/translate ## 0 0
/mesh/modify-zones/append-mesh-data " "

Then I start merging zones and surfaces etc. I can merge the cell zones no issue. But there is a huge memory leak when I try to fuse the overlapping boundaries and the interior zones.

/mesh/modify-zones/merge-ones fluid-1 fluid-1.1
this usually works okay. The next two always give me problems.
/mesh/modify-zones/fuse-face-zones wall-1 wall-1.1
/mesh/modify-zones/merge-zones interior interior.1

My mesh is currently only 7 million cells (x2=14 million). It shouldn't need more than 30 GB. However, when I run fuse-face-zones or try to do merge-zones on the interior I get a memory leak and the sim just asks for all the memory that is available >250GB RAM. Usually the fuse-face-zones will work (but uses ~210GB of RAM) and then the merge-zones interior will crash on a cortex error, probably because Fluent ran out of memory. In parallel goes just grabs all the RAM and crashes. In serial, it immediately throws a segmentation fault without hogging the memory.
souhail likes this.

Last edited by LuckyTran; June 11, 2017 at 15:28.
LuckyTran is offline   Reply With Quote

Old   June 6, 2017, 21:48
Default
  #2
Senior Member
 
Lucky Tran
Join Date: Apr 2011
Location: Orlando, FL USA
Posts: 1,821
Rep Power: 26
LuckyTran will become famous soon enoughLuckyTran will become famous soon enough
I had ANSYS support look into the issue.

It seems using /mesh/modify-zones/merge-zones on interior zones is a known bug in Fluent and is not recommended. Merging interior zones is only needed for tidiness anyway so it's not a high priority. However, merging boundary zones i.e. /mesh/modify-zones/fuse-face-zones should work.

I erroneously reported that fuse-face-zones ran into a memory leak. It actually doesn't but it does need a lot of memory. Performing fuse-face-zones roughly doubles the memory needed for the mesh (temporarily). ANSYS ran my case on a bigger node than mine, with 300+ GB of RAM and it still ran out of memory. Even for small grids, ANSYS recommends to never merge interior zones because of this memory requirement.

Last edited by LuckyTran; June 11, 2017 at 15:32.
LuckyTran 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
Star CCM Overset Mesh Error (Rotating Turbine) thezack CD-adapco 7 October 12, 2016 11:14
No layers in a small gap bobburnquist OpenFOAM Native Meshers: snappyHexMesh and Others 6 August 26, 2015 09:38
Possible Bug in pimpleFoam (or createPatch) (or fluent3DMeshToFoam) cfdonline2mohsen OpenFOAM 3 October 21, 2013 09:28
Using Workbench, CFX-Pre doesn't update mesh from upstream data Shawn_A CFX 2 November 25, 2012 14:06
2D Mesh Generation Tutorial for GMSH aeroslacker Open Source Meshers: Gmsh, Netgen, CGNS, ... 12 January 19, 2012 04:52


All times are GMT -4. The time now is 02:07.