CFD Online URL
[Sponsors]
Home > Forums > OpenFOAM Running, Solving & CFD

How can i perfoa a steady caculation

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

Reply
 
LinkBack Thread Tools Display Modes
Old   August 9, 2005, 05:48
Default thank you very much
  #1
Senior Member
 
ztdep's Avatar
 
p ding
Join Date: Mar 2009
Posts: 264
Rep Power: 8
ztdep is on a distinguished road
Send a message via Yahoo to ztdep Send a message via Skype™ to ztdep
thank you very much
ztdep is offline   Reply With Quote

Old   August 9, 2005, 16:50
Default I know SimpleFoam allows stead
  #2
Senior Member
 
Billy
Join Date: Mar 2009
Posts: 167
Rep Power: 7
billy is on a distinguished road
I know SimpleFoam allows steady state calculation. What do you want to simulate?
billy is offline   Reply With Quote

Old   August 10, 2005, 00:11
Default i want to simulate the most si
  #3
Senior Member
 
ztdep's Avatar
 
p ding
Join Date: Mar 2009
Posts: 264
Rep Power: 8
ztdep is on a distinguished road
Send a message via Yahoo to ztdep Send a message via Skype™ to ztdep
i want to simulate the most simple case "


"laminar lid driven cavity"

thank you very much,
ztdep is offline   Reply With Quote

Old   August 10, 2005, 01:32
Default Use simpleFoam, switching off
  #4
Senior Member
 
Alberto Passalacqua
Join Date: Mar 2009
Location: Ames, Iowa, United States
Posts: 1,890
Rep Power: 25
alberto will become famous soon enoughalberto will become famous soon enough
Use simpleFoam, switching off turbulence and choosing "laminar" as turbulence model.

Good work,
Alberto
__________________
Alberto

GeekoCFD - A free distribution based on openSUSE 64 bit with CFD tools, including OpenFOAM. Available as live DVD/USB, hard drive image and virtual image.
GeekoCFD 32bit - The 32bit edition of GeekoCFD.
GeekoCFD text mode - A smaller version of GeekoCFD, text-mode only, with only OpenFOAM. Available in a variety of virtual formats.
alberto is offline   Reply With Quote

Old   August 10, 2005, 11:24
Default In icoFoam is already the lid
  #5
gellert
Guest
 
Posts: n/a
In icoFoam is already the lid driven cavity implemented as example/tutorial case. And you
don't have any unnecessary turbulence models.
Furthermore take a look into the UserGuide, it describes the cavity case very comprehensive.

-marcus
  Reply With Quote

Old   August 11, 2005, 02:08
Default but how to simulate a steady p
  #6
Senior Member
 
ztdep's Avatar
 
p ding
Join Date: Mar 2009
Posts: 264
Rep Power: 8
ztdep is on a distinguished road
Send a message via Yahoo to ztdep Send a message via Skype™ to ztdep
but how to simulate a steady problem use the icofoam solver.

i have tried a very large time step with the implicit EULER scheme, but i always divergence.

but the implicit scheme shold convenge at any time step
ztdep is offline   Reply With Quote

Old   August 11, 2005, 05:11
Default icoFoam uses the PISO pressure
  #7
Senior Member
 
Join Date: Mar 2009
Posts: 854
Rep Power: 12
henry is on a distinguished road
icoFoam uses the PISO pressure-velocity coupling algorithm which is an efficient semi-implicit method for transient simulations but is not stable for very large time steps. This is not a proablem because very large time steps are not appropriate for transient flows.

simpleFoam is for steady-state flows and used the SIMPLE pressure-velocity algorithm which is efficient for this purpose.

If you insist on using a transient solver for steady-state flows you will have to write one using the transient SIMPLE algorithm which effectively means substituting the SIMPLE algorithm from simpleFoam into the time loop of icoFoam and introduce a convergence criterion. Although this will be stable for very large time-steps it is not an efficient way to solve steady-state problems.
henry is offline   Reply With Quote

Old   August 11, 2005, 07:37
Default What would be the best way to
  #8
New Member
 
Charles Crosby
Join Date: Mar 2009
Location: Cape Town, Western Cape, South Africa
Posts: 5
Rep Power: 7
crosby is on a distinguished road
What would be the best way to get to a compressible steady solver? sonicTurbFoam needs very small time steps, thus a rather large number of them to get to a steady state solution. How difficult is it likely to be to implement a form of local time stepping?
crosby is offline   Reply With Quote

Old   August 11, 2005, 11:06
Default rhoSimpleFoam can be used for
  #9
Senior Member
 
Join Date: Mar 2009
Posts: 854
Rep Power: 12
henry is on a distinguished road
rhoSimpleFoam can be used for sub-sonic compressible steady flows but for super-sonic cases under-relaxation is problematic and local time stepping may be a better option. We are investigating this at the moment.
henry is offline   Reply With Quote

Old   August 11, 2005, 19:17
Default Does anybody have some example
  #10
New Member
 
Charles Crosby
Join Date: Mar 2009
Location: Cape Town, Western Cape, South Africa
Posts: 5
Rep Power: 7
crosby is on a distinguished road
Does anybody have some example setup files for rhoSimpleFoam?
crosby is offline   Reply With Quote

Old   March 21, 2006, 04:15
Default Hi Henry, did you mean rhoS
  #11
Member
 
VVqf
Join Date: Mar 2009
Location: Braunschweig
Posts: 66
Rep Power: 7
vvqf is on a distinguished road
Hi Henry,

did you mean rhoSonicFoam by "rhoSimpleFoam" ?

and what did you mean for super-sonic cases?
did you mean for super-sonic compressible steady flows, "rhoSimpleFoam" can also be used by local time stepping as a better option, rather than sonicFoam, which is but a transient solver?
vvqf is offline   Reply With Quote

Old   September 15, 2006, 10:21
Default Hi everyone! Could anyone t
  #12
tak
New Member
 
taka
Join Date: Mar 2009
Location: Japan
Posts: 7
Rep Power: 7
tak is on a distinguished road
Hi everyone!

Could anyone teach me the physical meaning of
- fvm::Sp(fvc::div(phi), U)
in UEqn.H, and
fvc::div(phi/fvc::interpolate(rho)*fvc::interpolate(p))
- p*fvc::div(phi/fvc::interpolate(rho))

in hEqn.H of rhoSimpeFoam.

Thank you.
tak is offline   Reply With Quote

Old   May 12, 2010, 14:08
Default
  #13
Member
 
KGN
Join Date: Oct 2009
Location: Chennai, India
Posts: 95
Rep Power: 7
mecbe2002 is on a distinguished road
Hi all,

I am also interested in implementation of local time stepping. Even though its a very very old post, i hope you people will reply.

Can you suggest me some guideline to implement local time stepping for "rhoSonicFoam" OpenFOAM 1.6 solver.

thanks
mecbe
mecbe2002 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
headloss caculation problem majie023 FLUENT 0 September 9, 2006 10:12
Area caculation in Fluent? mimibenben FLUENT 5 July 12, 2006 23:07
some problem about caculation of quadrature ztdep Main CFD Forum 4 March 8, 2006 18:58
udf for acoustic caculation kevin FLUENT 0 September 29, 2005 23:32
caculation of friction factor Dilip Main CFD Forum 8 May 5, 2001 01:42


All times are GMT -4. The time now is 16:47.