CFD Online Logo CFD Online URL
www.cfd-online.com
[Sponsors]
Home > Forums > FLOW-3D

multi block error

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

Reply
 
LinkBack Thread Tools Display Modes
Old   December 10, 2011, 02:35
Default multi block error
  #1
ava
New Member
 
S.Elyasi
Join Date: Jun 2011
Location: IRAN
Posts: 11
Rep Power: 6
ava is on a distinguished road
dear all
i work in a model with multi block method
but i dont know why the multi block error(mlbk error) is so great?
ava is offline   Reply With Quote

Old   December 12, 2011, 01:43
Default
  #2
Senior Member
 
michael barkhudarov
Join Date: Mar 2009
Posts: 331
Rep Power: 9
MuxaB is on a distinguished road
you mean volume error? The error is computed by comparing the flow rate on each side of an inter-block boundary and summing it over all inter-block boundaries.

The error would be non-zero if the flow rate do not match, and may be more so if any of the following is happening:

1. large change in mesh resolution between adjacent mesh blocks
2. significant fluid break up at the boundary
3. poor convergence of the pressure solver

What version are you running? There is also ain input variable called inter-block boundary interpolation coefficient whose value varies from 0 to 1, with the default value of 0.25. You may want to raise it to get volume conservation.
MuxaB is offline   Reply With Quote

Old   December 12, 2011, 02:16
Default question
  #3
ava
New Member
 
S.Elyasi
Join Date: Jun 2011
Location: IRAN
Posts: 11
Rep Power: 6
ava is on a distinguished road
hi and thanks
my software version is 9.3
in iran i couldn't find 9.4 version of it
where is inter-block boundary interpolation coefficient
is necessary to check it?
what is the allaowable limitation of it?
ava
whit the best regards
ava is offline   Reply With Quote

Old   December 12, 2011, 12:06
Default
  #4
Senior Member
 
michael barkhudarov
Join Date: Mar 2009
Posts: 331
Rep Power: 9
MuxaB is on a distinguished road
it's under Numerics > Convergence Controls for pressure solvers, at the very bottom. If you did not change it, it must be at the default, which usually works fine. When it is =0, the coupling between blocks is done only through pressure, when it is =1 - through velocity. The default of 0.25 means 25% velocity and 75% pressure.
MuxaB 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
CGNS Compiling Diego Main CFD Forum 17 December 21, 2014 02:40
GroovyBC the dynamic cousin of funkySetFields that lives on the suburb of the mesh gschaider OpenFOAM 300 October 29, 2014 19:00
c++ libraries and solver compiling vaina74 OpenFOAM Installation 13 February 3, 2012 18:43
Installation OF1.5-dev ttdtud OpenFOAM Installation 46 May 5, 2009 02:32
OpenFOAM on MinGW crosscompiler hosted on Linux allenzhao OpenFOAM Installation 127 January 30, 2009 20:08


All times are GMT -4. The time now is 19:30.