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

Problem of calculating divergence due to wrong boundary vaule of finite area mesh

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

Reply
 
LinkBack Thread Tools Display Modes
Old   April 24, 2015, 08:25
Default Problem of calculating divergence due to wrong boundary vaule of finite area mesh
  #1
New Member
 
Lu ZHOU
Join Date: Jul 2014
Location: Lyon, France
Posts: 8
Rep Power: 3
lzhou is on a distinguished road
Hi,

I am using Finite area method to simulate the scour on river bed.

When calculating the divergence of an "areaVectorField" Qsa (fac::div(Qsa)), I found out that the program suppose the Qsa value at the boundary of the finite area mesh is (0 0 0), even though I set the boundary condition of Qsa as zeroGradient in file 0/Qsa. So the divergence calculated is not correct at the boundary of finite area mesh.

I would like to ask how to solve this problem ? Or is there a way to get the label of the face cell at the boundary of the finite area mesh and correct it ? Thanks !

Lu ZHOU
Attached Images
File Type: jpg 1.jpg (15.5 KB, 12 views)
File Type: jpg 2.jpg (13.7 KB, 8 views)
lzhou is offline   Reply With Quote

Old   June 17, 2015, 09:00
Default
  #2
New Member
 
Tian Tang
Join Date: Jun 2012
Location: Copenhagen, Denmark
Posts: 16
Rep Power: 5
tiat is on a distinguished road
HI LU,

I am having the same problem as you described and I wonder have you figured out a solution yet? Thanks!
tiat is offline   Reply With Quote

Old   June 18, 2015, 05:10
Default
  #3
New Member
 
Lu ZHOU
Join Date: Jul 2014
Location: Lyon, France
Posts: 8
Rep Power: 3
lzhou is on a distinguished road
Hello,

I asked someone else and the answer I got was that the boundary of finite area method did obey the zeroGradient boundary condition. So I think the problem is when we use vsm.mapToSurface(), only the internal field is mapped but not the boundary values. So I set the boundary value by myself because in my case I just need to set the boundary value to zero.

I would like to find someway to modify the boundary values as a function in finite volume mesh like U.correctBoundaryCondition() but I couldn't find one. If you get some better ways to solve this please let me know.

Best regards !

Lu
lzhou 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
snappyhexmesh remove blockmesh geometry philipp1 OpenFOAM Running, Solving & CFD 2 December 12, 2014 11:58
Question about heat transfer coefficient setting for CFX Anna Tian CFX 1 June 16, 2013 06:28
Error finding variable "THERMX" sunilpatil CFX 8 April 26, 2013 07:00
[ICEM] Problem making structural mesh on a surface froztbear ANSYS Meshing & Geometry 1 November 10, 2011 09:52
Convective Heat Transfer - Heat Exchanger Mark CFX 6 November 15, 2004 16:55


All times are GMT -4. The time now is 11:05.