|
[Sponsors] |
What does low frequency oscillation phenomena tell in residuals |
|
LinkBack | Thread Tools | Search this Thread | Display Modes |
July 24, 2013, 04:10 |
What does low frequency oscillation phenomena tell in residuals
|
#1 |
Member
hekseli
Join Date: Mar 2013
Posts: 49
Rep Power: 13 |
Hey!
I was wondering what creates a low frequency oscillation in residuals like in the particular image as an attachment. I would bet that it is due to a coarse mesh x-direction, because y-direction velocity is not oscillating so much and because turbulence quantities are no converging as quickly. I just have never seen such a low frequency phenomena, though beginner I am. |
|
July 24, 2013, 04:34 |
|
#2 |
Senior Member
Filippo Maria Denaro
Join Date: Jul 2010
Posts: 6,764
Rep Power: 71 |
If you think that the computational grid acts as a cut-off filtering and the numerical schemes smoothes high resolved frequencies, then it is quite common that the spectrum of the error will be dumped quickly at high frequancy and slowly at low frequencies.
In some way, this is at basis of the multigrid ideas, resolve the equations on wider grids to smooth more quick the low frequencies of the error. In your case I suppose that the error is more "energetic" along x than along y |
|
July 24, 2013, 18:00 |
|
#3 |
Senior Member
Martin Hegedus
Join Date: Feb 2011
Posts: 500
Rep Power: 19 |
Looks like a separation bubble trying to converge.
|
|
|
|
Similar Threads | ||||
Thread | Thread Starter | Forum | Replies | Last Post |
The oscillation of scaled residuals is very big | ZQWY | FLUENT | 0 | February 16, 2012 21:00 |
extremely low residuals | ranjith | CFX | 2 | March 4, 2010 05:45 |
Oscillation of residuals in DPM (Ergent need!) | yooceframandi | FLUENT | 1 | February 28, 2006 06:46 |
Multicomponent fluid | Andrea | CFX | 2 | October 11, 2004 05:12 |
jet oscillation at low inlet Re | wood | Main CFD Forum | 1 | October 21, 1999 13:45 |