CFD Online Logo CFD Online URL
www.cfd-online.com
[Sponsors]
Home > Forums > Software User Forums > OpenFOAM > OpenFOAM Running, Solving & CFD

Measuring numerical diffusion and dispersion - strange effects

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

Reply
 
LinkBack Thread Tools Search this Thread Display Modes
Old   March 31, 2009, 17:51
Default Measuring numerical diffusion and dispersion - strange effects
  #1
New Member
 
Chris Beck
Join Date: Mar 2009
Posts: 4
Rep Power: 17
cbeck is on a distinguished road
Hello,

I was attempting to measure numerical diffusion and dispersion when I encountered unexpected behavior. The test case is attached.

The test case is a 1D case. An acoustic wave is initialized. Cyclic boundary conditions are used in the direction of wave propagation. In the example 30 wave lengths are fit into the domain. The compressible solver coodles is used. A small acoustic CFL number of 0.2 is set. In general, solver parameters are set to overly conservative values. Then I intended to compare the analytical time series for the pressure at a monitor point with the numerical solution.

Oddly, I found mean pressure, velocity as well as temperature to increase during the run time.

For typical solver parameters, results are much worse. I would realy like to know if this is an issue of the setup or the code and would appreciate your input.

regards,
Christian
Attached Files
File Type: gz test_wave_30.tar.gz (44.0 KB, 9 views)
cbeck 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
convection, diffusion, advection, dispersion Lam Main CFD Forum 7 May 18, 2007 13:04
HELP: diffusion & dispersion of particle method QU KUN Main CFD Forum 0 January 22, 2004 02:21


All times are GMT -4. The time now is 19:37.