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

solver setting

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

Reply
 
LinkBack Thread Tools Display Modes
Old   July 26, 2012, 17:04
Default solver setting
  #1
New Member
 
nabizadeh
Join Date: May 2012
Location: iran
Posts: 21
Rep Power: 5
eb.nabizadeh is on a distinguished road
can any one help me please?
i have a 3D model(a house)that i want to check temp & flow in it.my model is transient & the volume of it is 400m3,walls are at initial temp 20 c and when wind blowing into it exchange it's heat with walls.but i have some problem in convergence.i want some one to say exact setting about my model.what under-relaxation factor is good for it,which viscose model is better.finally what must i do to converge my problem.thanks
eb.nabizadeh is offline   Reply With Quote

Old   July 26, 2012, 17:15
Default
  #2
New Member
 
nabizadeh
Join Date: May 2012
Location: iran
Posts: 21
Rep Power: 5
eb.nabizadeh is on a distinguished road
i don't have much time please help me early
eb.nabizadeh is offline   Reply With Quote

Old   July 27, 2012, 02:12
Default
  #3
Senior Member
 
Bionico's Avatar
 
Flavio
Join Date: Sep 2011
Location: Brescia, Italy
Posts: 181
Rep Power: 5
Bionico is on a distinguished road
Hello
If I were you I would try first with a k-epsilon model (Realizable o RNG).
Maybe it's better to reduce the URF (M=0.2 E=0.9 should be enough).
First order upwind for discretization and PRESTO! for pressure scheme.
Bionico is offline   Reply With Quote

Old   July 27, 2012, 03:55
Default
  #4
Member
 
Join Date: Nov 2011
Location: Czech Republic
Posts: 95
Rep Power: 5
Sixkillers is on a distinguished road
Also It depends which model you use for air density. Are using ideal gas model or Boussinesq approximation? Generally speaking ideal gas model is harder to converge.
Sixkillers is offline   Reply With Quote

Old   July 27, 2012, 09:50
Default
  #5
New Member
 
nabizadeh
Join Date: May 2012
Location: iran
Posts: 21
Rep Power: 5
eb.nabizadeh is on a distinguished road
i use Boussinesq model for density.i want to know what criterion(surface integrals) can i consider except residual?
eb.nabizadeh is offline   Reply With Quote

Old   July 28, 2012, 04:16
Default
  #6
New Member
 
nabizadeh
Join Date: May 2012
Location: iran
Posts: 21
Rep Power: 5
eb.nabizadeh is on a distinguished road
dear Bionico
when in do what you said i facing this error:floating point exception!
and when i change my turbulence model it didn't converge.
can you help me more?
eb.nabizadeh is offline   Reply With Quote

Old   July 30, 2012, 02:42
Default
  #7
Senior Member
 
Bionico's Avatar
 
Flavio
Join Date: Sep 2011
Location: Brescia, Italy
Posts: 181
Rep Power: 5
Bionico is on a distinguished road
ok, it's a convergence problem...
since this is a transient simulation, try reducing the Courant number under 1
Bionico is offline   Reply With Quote

Old   July 30, 2012, 17:45
Smile
  #8
New Member
 
nabizadeh
Join Date: May 2012
Location: iran
Posts: 21
Rep Power: 5
eb.nabizadeh is on a distinguished road
you mean i use density based or pressure based?
eb.nabizadeh is offline   Reply With Quote

Old   July 31, 2012, 02:01
Default
  #9
Senior Member
 
Bionico's Avatar
 
Flavio
Join Date: Sep 2011
Location: Brescia, Italy
Posts: 181
Rep Power: 5
Bionico is on a distinguished road
No, but maybe (I don't remember very well) the Courant number can be controlled only in COUPLED problem (not if you have a SIMPLE one).
Therefore try reducing time step and increasing number of iteration/time step
Bionico 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
A New Solver for Supersonic Combustion nakul OpenFOAM 6 March 30, 2014 03:00
Quarter Burner mesh with periosic condition SamCanuck FLUENT 2 August 31, 2011 11:34
Working directory via command line Luiz CFX 4 March 6, 2011 21:02
Cells with t below lower limit Purushothama CD-adapco 2 May 31, 2010 21:58
why the solver reject it? Anyone with experience? bearcat CFX 6 April 28, 2008 14:08


All times are GMT -4. The time now is 09:50.