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

slope limiter of discontinuous galerkin

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

Reply
 
LinkBack Thread Tools Search this Thread Display Modes
Old   September 29, 2011, 03:33
Default slope limiter of discontinuous galerkin
  #1
New Member
 
Join Date: Sep 2011
Posts: 11
Rep Power: 14
zqb0929 is on a distinguished road
Hello,friends! I'm a newcomer. I'm using discontinuous galerkin to compute shallow water equations. Because of the nonphysical oscillation I use a slope limiter. But I don't know how to use the limiter in the triangular cells around the boundary. I would appreciate any advice. Thanks!
zqb0929 is offline   Reply With Quote

Old   September 29, 2011, 17:14
Default
  #2
New Member
 
aaaaaaaaaaaaaa
Join Date: Apr 2011
Posts: 23
Rep Power: 14
panou is on a distinguished road
If you solve the 2d equations you have only quadrilateral and triangle elements. For both two type of elements cockburn & Shu have been developed in their papers (multidimensional case) a methodology for slope limiting. At quadrilaterals is more straightforward while at the triangles is not.

Mainly, the limiting procedure applied when in solution domain exist discontinuities (shocks,contacts..) which created very large oscillations and large slopes. If you have discontinuities (such as by initial solution or other) then you must apply limiting procedure.If not, maybe, will be better to use a artificial viscosity because the limiting reduce the accuracy at most first order regardless if you use high order basis.

If you want give me your skype name or msn so that talk about it with more details. The limiting procedure has more aspects and is very complicate.
panou is offline   Reply With Quote

Old   September 30, 2011, 05:29
Smile
  #3
New Member
 
Join Date: Sep 2011
Posts: 11
Rep Power: 14
zqb0929 is on a distinguished road
Thank you, Panou! Here is the thing: I know the slope limiter you mentioned. You know the implementation of slope limiter on one cell needs the cell-averaged values of its three neighboring cells. It is obviously ok when the cell is a inner cell but if the cell is a boundary cell there lacks one cell. Although DGM uses ghost-cell method to compute the numerical flux around the boundary, I can't find out some preferences on how to apply the limiters to the boundary cells. I want to get some guidance about the question above. Thanks again!
zqb0929 is offline   Reply With Quote

Old   September 30, 2011, 05:40
Smile
  #4
New Member
 
Join Date: Sep 2011
Posts: 11
Rep Power: 14
zqb0929 is on a distinguished road
In addition, I use a slope limiter mentioned in "New two-dimensional slope limiters for discontinuous Galerkin methods on arbitrary meshes".
zqb0929 is offline   Reply With Quote

Old   October 1, 2011, 07:18
Default
  #5
Member
 
kostas
Join Date: Jun 2010
Posts: 43
Rep Power: 15
pankos is on a distinguished road
Look. At boundaries cells you can take zero of average differences and thus to operate the ghost element. With other words, you can take the mean of ghost equal to mean of boundary cell.
There is not problem with this.

if you want give me a name for skype to talk here.
pankos is offline   Reply With Quote

Old   October 2, 2011, 08:29
Talking
  #6
New Member
 
Join Date: Sep 2011
Posts: 11
Rep Power: 14
zqb0929 is on a distinguished road
Thank friends. my msn is shallowwaterlake@hotmail.com and it is just registered.
Skype: zqb2011

Last edited by zqb0929; October 5, 2011 at 05:59.
zqb0929 is offline   Reply With Quote

Old   October 2, 2011, 08:37
Default
  #7
New Member
 
Join Date: Sep 2011
Posts: 11
Rep Power: 14
zqb0929 is on a distinguished road
Friends from the U.S.? MSN and SKYPE may be used widespreadly but I am from China and I am not familiar with those tools.
zqb0929 is offline   Reply With Quote

Old   October 5, 2011, 06:05
Default
  #8
New Member
 
Join Date: Sep 2011
Posts: 11
Rep Power: 14
zqb0929 is on a distinguished road
Hi,Friends, are there any group of Skype?
zqb0929 is offline   Reply With Quote

Reply

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
Runge Kutta Discontinuous Galerkin procedure? Ameya J Main CFD Forum 6 July 29, 2011 06:56
slope limiter and flux limiter ?? Ameya J Main CFD Forum 1 June 13, 2011 13:05
Discontinuous Galerkin schemes -- fortran source code diedro Main CFD Forum 3 March 12, 2011 11:20
Discontinuous Galerkin for viscous Navier-Stokes Junseok Kim Main CFD Forum 9 September 15, 2004 11:17
Discontinuous Galerkin finite element method Tony Main CFD Forum 0 May 27, 2003 19:48


All times are GMT -4. The time now is 18:06.