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

LES simulation parameters

Register Blogs Community New Posts Updated Threads Search

Reply
 
LinkBack Thread Tools Search this Thread Display Modes
Old   May 20, 2016, 10:57
Default LES simulation parameters
  #1
Member
 
Manjunath Reddy
Join Date: Jun 2013
Posts: 47
Rep Power: 13
manju819 is on a distinguished road
Hi Foamers,

I'm currently working on fireFoam. I'm trying to compare the results of fireFoam with the Fire Dynamic Simulator (FDS) which is well known tool for fire modelling. fireFoam and FDS both uses the Large Eddy Simulations for turbulence modelling. Coming to the case part I considered a small room of 0.4 mx0.4 mx0.4 m with the burner of size 0.08x0.08 m2. Four sides of room are open and top of the room is closed. I defined same fire source in fireFoam and FDS. If I see the results of temperature contour(Attached fireFoam_T_75s.png) from both the solvers in fireFoam the temperature is uniform along the Z no fluctuation yet all. If I see the temperature plot in FDS(Attached PoolFire_FDS_T75s.png) it is fluctuating in X and Y along the Z direction and breaking into eddies.

What might be causing the temperature(Velocity is also uniform) to be uniform in fireFoam where as nonuniform in FDS? Is it because of LES turbulence parameters?


If I want to make the flow to break into eddies in fireFoam what parameters are to be changed in the LES model?


Please help me.

Thanks
Manjunath Reddy N
Attached Images
File Type: jpg Geometry.jpg (27.8 KB, 23 views)
File Type: jpg PoolFire_FDS_T_75s.jpg (42.7 KB, 34 views)
File Type: jpg fireFoam_T_75s.jpg (53.0 KB, 29 views)
manju819 is offline   Reply With Quote

Old   May 23, 2016, 05:05
Default
  #2
Senior Member
 
Tom Fahner
Join Date: Mar 2009
Location: Breda, Netherlands
Posts: 647
Rep Power: 32
tomf will become famous soon enoughtomf will become famous soon enough
Send a message via MSN to tomf Send a message via Skype™ to tomf
I know that FDS introduces a fluctuation as a random background noise but probably also introduces a random fluctuation at the burner vent. You should probably do something similar for the inlet patch for the fireFoam calculation. This may work with a turbulentInlet

see:
$FOAM_SRC/finiteVolume/fields/fvPatchFields/derived/turbulentInlet/turbulentInletFvPatchField.H
tomf is offline   Reply With Quote

Old   May 23, 2016, 07:14
Default
  #3
Member
 
Manjunath Reddy
Join Date: Jun 2013
Posts: 47
Rep Power: 13
manju819 is on a distinguished road
Hi Tom Fahner,

Thank you very much for your valuable reply. Yes Tom, FDS introduces Noise which breaks the symmetry. It might also introducing some random fluctuations.

Actually I defined flowRateInletVelocity boundary condition at the burner now if want to add the turbulentInlet boundary condition along with the flowRateInletVelocity is it possible?


Thanks
Manjunath Reddy N
manju819 is offline   Reply With Quote

Old   May 23, 2016, 08:05
Default
  #4
Senior Member
 
Tom Fahner
Join Date: Mar 2009
Location: Breda, Netherlands
Posts: 647
Rep Power: 32
tomf will become famous soon enoughtomf will become famous soon enough
Send a message via MSN to tomf Send a message via Skype™ to tomf
Hi Manjunath Reddy N,

Unfortunately that is not possible. The flowRateInletVelocity boundary condition does allow a time varying (spatially uniform) flowrate to be used, so you might be able to make it fluctuate in time. Another option would be to use groovyBC (look around on the forum) or calculate the average velocity upfront and use the turbulentInlet with that. Or you would need to generate a new boundary condition that combines the functionality of the flowRateInletVelocity with the turbulentInlet.

Regards,
Tom
tomf is offline   Reply With Quote

Old   May 26, 2016, 03:24
Default
  #5
Member
 
Manjunath Reddy
Join Date: Jun 2013
Posts: 47
Rep Power: 13
manju819 is on a distinguished road
Hi Tom,

Thank you for your reply, I will work out on implementing boundary condition using swak4Foam.


Thank you
Manjunath
manju819 is offline   Reply With Quote

Old   November 6, 2016, 09:07
Default fire simulation
  #6
New Member
 
razieh khaksari
Join Date: Oct 2016
Posts: 4
Rep Power: 10
baran khaksari is on a distinguished road
Hi friends
I just start to use OpenFOAM and want to simulate a pool fire in a compartment. But I do not know how can I start and which tutorial can help me?
Please help me.
In do not want use fireFoam.
thank you.
baran khaksari is offline   Reply With Quote

Reply


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
How to make grid for LES simulation dinhanh Main CFD Forum 3 November 11, 2015 03:37
Les transient simulation (loading) juliom Tecplot 6 August 31, 2015 15:45
2D LES simulation of turbulent jet adnan.nweilati FLUENT 6 December 3, 2014 10:33
How to conduct transient LES simulation tianrenshui311 FLUENT 0 November 15, 2010 14:21
continue LES simulation after it stopped holand_us OpenFOAM 9 April 5, 2010 13:52


All times are GMT -4. The time now is 22:09.