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

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

April 24, 2015, 08:25
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
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
 1.jpg (15.5 KB, 12 views) 2.jpg (13.7 KB, 8 views)

 June 17, 2015, 09:00 #2 New Member   Tian Tang Join Date: Jun 2012 Location: Copenhagen, Denmark Posts: 16 Rep Power: 5 HI LU, I am having the same problem as you described and I wonder have you figured out a solution yet? Thanks!

 June 18, 2015, 05:10 #3 New Member   Lu ZHOU Join Date: Jul 2014 Location: Lyon, France Posts: 8 Rep Power: 3 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

 Thread Tools Display Modes Linear Mode

 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 OffTrackbacks are On Pingbacks are On Refbacks are On Forum Rules

 Similar Threads Thread Thread Starter Forum Replies Last Post philipp1 OpenFOAM Running, Solving & CFD 2 December 12, 2014 11:58 Anna Tian CFX 1 June 16, 2013 06:28 sunilpatil CFX 8 April 26, 2013 07:00 froztbear ANSYS Meshing & Geometry 1 November 10, 2011 09:52 Mark CFX 6 November 15, 2004 16:55

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