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

GGI in OpenFOAM

Register Blogs Community New Posts Updated Threads Search

Reply
 
LinkBack Thread Tools Search this Thread Display Modes
Old   April 2, 2009, 08:08
Default GGI in OpenFOAM
  #1
Senior Member
 
Hrvoje Jasak
Join Date: Mar 2009
Location: London, England
Posts: 1,907
Rep Power: 33
hjasak will become famous soon enough
Dear All,

I am happy to announce that I have now finished the implementation of the General Grid Interface (GGI) in OpenFOAM, including massive parallelisation and algebraic multigrid solver (this was a struggle). The SVN snapshot, including the updated tutorial will be uploaded later today.

Please note that as a part of parallelisation I have changed the domain decomposition tools AND the definition of the GGI - you will have to (slightly) update the existing cases.

Since GGI is pretty popular and quite tricky to set up, I would like to propose a skype teleconference with a demonstration, some background, tutorial and a series of slides on how to use the feature. Please drop me a line if you are interested and we at Wikki will do the organisation.

Many thanks to people who contributed to the code - you know who you are. I also expect to present the details of numerics, implementation and parallelisation on the Workshop in Montreal

Enjoy,

Hrv
__________________
Hrvoje Jasak
Providing commercial FOAM/OpenFOAM and CFD Consulting: http://wikki.co.uk
hjasak is offline   Reply With Quote

Old   April 2, 2009, 13:18
Default
  #2
Senior Member
 
BastiL
Join Date: Mar 2009
Posts: 530
Rep Power: 20
bastil is on a distinguished road
Hrv,

that sounds great to me. Thank you very much. I will give it a try soon.

Regards BastiL
bastil is offline   Reply With Quote

Old   April 7, 2009, 15:58
Default
  #3
Member
 
Hai Yu
Join Date: Mar 2009
Location: Harbin
Posts: 67
Rep Power: 17
yuhai is on a distinguished road
Quote:
Originally Posted by hjasak View Post
Dear All,


Since GGI is pretty popular and quite tricky to set up, I would like to propose a skype teleconference with a demonstration, some background, tutorial and a series of slides on how to use the feature. Please drop me a line if you are interested and we at Wikki will do the organisation.

Hrv
Thanks for all the efforts, and what is your skype account?
I am insterested in.
Anyone else?
yuhai is offline   Reply With Quote

Old   April 8, 2009, 16:18
Default
  #4
New Member
 
Helmut Roth
Join Date: Mar 2009
Posts: 23
Rep Power: 17
helmut is on a distinguished road
Hi Hrv,

This sounds good to me. Please put me on the list for the proposed teleconf.

Thanks,
Helmut
helmut is offline   Reply With Quote

Old   April 9, 2009, 09:27
Default
  #5
New Member
 
Mohammad Mojab
Join Date: Apr 2009
Posts: 1
Rep Power: 0
syed is on a distinguished road
Hello Hrv,

Thanks for this great work. I like to know more about Ggi, and how to work with that. Would you add my name to the list for teleconf?

Thank you
Mojab
syed is offline   Reply With Quote

Old   April 9, 2009, 18:20
Default
  #6
Senior Member
 
BastiL
Join Date: Mar 2009
Posts: 530
Rep Power: 20
bastil is on a distinguished road
Hrv,

I have run first tests now and everything works fine so far. Thank you very much.
bastil is offline   Reply With Quote

Old   April 14, 2009, 07:27
Default
  #7
Senior Member
 
Fabian Braennstroem
Join Date: Mar 2009
Posts: 407
Rep Power: 19
braennstroem is on a distinguished road
I would like to join you skype session, but have no webcam and never used it before. Is it possible to just listen and watch? Would be nice :-)

Fabian
braennstroem is offline   Reply With Quote

Old   April 14, 2009, 22:03
Default
  #8
Senior Member
 
lakeat's Avatar
 
Daniel WEI (老魏)
Join Date: Mar 2009
Location: Beijing, China
Posts: 689
Blog Entries: 9
Rep Power: 21
lakeat is on a distinguished road
Send a message via Skype™ to lakeat
I'd like to be in too
__________________
~
Daniel WEI
-------------
Boeing Research & Technology - China
Beijing, China
Email
lakeat is offline   Reply With Quote

Old   April 17, 2009, 07:27
Default
  #9
Member
 
Nick Gardiner
Join Date: Apr 2009
Location: Chichester, UK
Posts: 94
Rep Power: 17
NickG is on a distinguished road
Hi Hrv

Thanks for the huge amount of effort that this all must have taken. Would it be possible to record and post the video conference as a tutorial file in OpenFOAM? Also I am unable to find ggi on the subversion repository - What is it called and which package is it in?

Thanks again

Nick
NickG is offline   Reply With Quote

Old   April 17, 2009, 16:30
Default
  #10
Senior Member
 
Martin Beaudoin
Join Date: Mar 2009
Posts: 332
Rep Power: 22
mbeaudoin will become famous soon enough
Hello,

The GGI is now part of the main OpenFOAM-1.5-dev libraries, and is not provided as a separate package.

Martin

Quote:
Originally Posted by NickG View Post
Hi Hrv

Thanks for the huge amount of effort that this all must have taken. Would it be possible to record and post the video conference as a tutorial file in OpenFOAM? Also I am unable to find ggi on the subversion repository - What is it called and which package is it in?

Thanks again

Nick
mbeaudoin is offline   Reply With Quote

Old   April 19, 2009, 14:54
Default OpenFOAM GGI webcast
  #11
Senior Member
 
Hrvoje Jasak
Join Date: Mar 2009
Location: London, England
Posts: 1,907
Rep Power: 33
hjasak will become famous soon enough
Dear All,

Thank you for your responses, both through the Forum and directly. We have picked Thursday 14/May/2009 14.00 GMT for the webcast, which will be done as a teleconference + pdf slides.

To register, please E-mail enquiries@wikki.co.uk with your name, affiliation and contact details.

Hrv
__________________
Hrvoje Jasak
Providing commercial FOAM/OpenFOAM and CFD Consulting: http://wikki.co.uk
hjasak is offline   Reply With Quote

Old   April 20, 2009, 04:12
Default Thanks for your great work!
  #12
Senior Member
 
Håkan Nilsson
Join Date: Mar 2009
Location: Gothenburg, Sweden
Posts: 205
Rep Power: 18
hani is on a distinguished road
Hi,

I would like to thank you for this very useful development.

I'm sure that Martin Beaudoin 'knows who he is', but I would like to acknowledge him in name, as one of the guys who did much of the work.

Håkan.
hani is offline   Reply With Quote

Old   April 20, 2009, 04:36
Default missed OpenFOAM GGI webcast
  #13
New Member
 
Daniele Speziani
Join Date: Mar 2009
Location: Rivoli, TO, Italy
Posts: 3
Rep Power: 17
danielespezianiphitecingegneriait is on a distinguished road
Hi Hrv

Is there any available documentation about the GGI implementation, as video recordings or slides? Unfortunately I missed the webcast!

Thanks again

Daniele
danielespezianiphitecingegneriait is offline   Reply With Quote

Old   April 20, 2009, 05:36
Default
  #14
Member
 
Marco Müller
Join Date: Mar 2009
Location: Germany
Posts: 94
Rep Power: 17
marico is on a distinguished road
Thats really crazy, Daniele... Tell me how to live in future...
marico is offline   Reply With Quote

Old   April 20, 2009, 05:46
Default
  #15
New Member
 
Daniele Speziani
Join Date: Mar 2009
Location: Rivoli, TO, Italy
Posts: 3
Rep Power: 17
danielespezianiphitecingegneriait is on a distinguished road
Marico,

You are right, and fortunately I am living in the present with some look to the future . I just have not read the month correctly.
In any case Hrv please add me into your list

Daniele

Quote:
Originally Posted by marico View Post
Thats really crazy, Daniele... Tell me how to live in future...
danielespezianiphitecingegneriait is offline   Reply With Quote

Old   April 29, 2009, 12:25
Default GGI user report
  #16
New Member
 
Mikko Auvinen
Join Date: Mar 2009
Location: Helsinki, Finland
Posts: 8
Rep Power: 17
auvinen is on a distinguished road
First, I'd like to applaud Martin Beaudoin and Hrvoje Jasak for their amazing efforts with the GGI. Truly inspiring work!

It's now time to expose the GGI to the real world and begin to accumulate the experiences. Here is my brief report which includes both success stories and problems. (The story will continue in Montreal, but hopefully without the problems section.)

Case:
A single-blade pump in a volute. Incompressible, turbulent flow.

Mesh:
Two separately generated GridPro meshes, one for the impeller (rotor) and the other for the volute (casing). Total number of cells appr. 1.15M and on the impeller avg. y+~=42 (wall functions). The GGI patches were completely non-matching: insideGGI/outsideGGI = 10080/9744 faces.

MRFSimpleFoam:
I had no difficulty setting up the problem and computing a quasi-steady (frozen-rotor) solution with both kEpsilon and kOmegaSST turbulence models. The error in the mass flux across the GGI was:
GGI pair (insideGGI, outsideGGI) : 0.0588090734 0.0588615586 Diff = -8.7289918e-05 or 0.148429338 %.

turbDyMFoam:
I managed to start a single-processor time-accurate run using the quasi-steady solution as an initial guess, but I had great difficulties keeping the pressure under control (now I know why). Once the pressure did settle - I had to use a very small time step - I managed to compute about 1.2 revolutions with the deltaT corresponding to 0.5deg per time step. So, the GGI seems to work! The pressure behavior continued to be 'noisy', but remained sensible as you can see in the picture (head.jpg).

I stopped to update my dev installation to this latest version and followed the mixerGgi-tutorial's example in changing the setup. (Btw, the zone treatment is now much better than before.) I think I got everything right, but when I restarted the time-accurate computation, the pressure problems came back two fold. Now that I had to dig a bit deeper I noticed the following:

1. Mass flux (phi) across the impeller wall is, clearly, not zero.
2. Uz on the impeller wall is not zero. (The rotation axis is the z-axis.) See the picture (Uz_impeller.jpg). In fact, they had not been zero since I started the turbDyMFoam run.

I've checked my case setup many times, but I cannot find anything wrong with it. The wall velocities worked beautifully with the MRFSimpleFoam computations. So, I guess there is a bug in the mixerGgiFvMesh, but I'm unable to identify it. Perhaps this is a enough for Hrv and Martin to get to the bottom of this. The tutorial is 2D so it doesn't yield any help on this. Has anyone else seen something like this?

This story will continue in Montreal, where I hope to present something good. I hope this problem has an easy fix -- perhaps at my end.

Best regards,
- mikko
Attached Images
File Type: jpg head.jpg (17.9 KB, 181 views)
File Type: jpg Uz_impellerWall.jpg (15.5 KB, 191 views)
File Type: jpg Uz_impellerWall2.jpg (13.8 KB, 177 views)

Last edited by auvinen; May 28, 2009 at 09:08.
auvinen is offline   Reply With Quote

Old   April 29, 2009, 14:50
Default
  #17
Member
 
olivier Petit
Join Date: Mar 2009
Location: Göteborg, Sweden
Posts: 67
Rep Power: 17
olivier is on a distinguished road
Hi Mikko

We are doing similar simulations except that I stayed in 2D for now. I did use MRFSimpleFoam and turbDyMFoam as well, using the ggi, and I had the same problem than you, having trouble with the pressure. I came to the same conclusion than you, having a small time step solves the problem, and that is quite logical, as the mesh is physically moving, the time step should be so that you rotate the mesh not more than one or two cells each step.

However, as I am in 2D I didn't see the problem with the walls, but I have seen a case quite recently where the wall boundaries were not correctly set, but it still worked in MRFSimpleFoam, as nothing really turned.
Did you put a zeroGradient for the pressure on your walls, and a fixedValue (0 0 0) for the velocity at the wall?

Good luck!

Olivier
olivier is offline   Reply With Quote

Old   April 30, 2009, 04:19
Default
  #18
New Member
 
Mikko Auvinen
Join Date: Mar 2009
Location: Helsinki, Finland
Posts: 8
Rep Power: 17
auvinen is on a distinguished road
Hi Olivier,

The tangential velocities on the rotating wall computed by MRFZone (for MRFSimpleFoam) and mixerGgiFvMesh (for turbDyMFoam) agree nicely. It's the z-direction that is faulty. It can be easily seen how the wall velocities are computed by the MRFZone, but I cannot say the same about mixerGgiFvMesh. Hopefully someone with greater code fluency can bring further light onto this issue.

I added a new picture with a tighter scale to show how the Uz follows the z-component of the face normals, with maximum/minimum values around 45deg. If you're working with 2D geometries, you won't see this at all. You wouldn't have any 3D geometries lying around?

Perhaps the cylindrical coordinate system is at the root of this problem.

Yours,
- mikko
auvinen is offline   Reply With Quote

Old   April 30, 2009, 10:03
Default
  #19
Member
 
olivier Petit
Join Date: Mar 2009
Location: Göteborg, Sweden
Posts: 67
Rep Power: 17
olivier is on a distinguished road
Hi Mikko

I see what you mean. As you said with my 2D geometry, I don't have this problem. I do however have a 3D geometry of the ercoftac pump, meshed already, maybe I could share it with you if you want. I need to clean it a bit though and to work on it a bit first.

Olivier
olivier is offline   Reply With Quote

Old   April 30, 2009, 14:38
Default
  #20
Senior Member
 
Hrvoje Jasak
Join Date: Mar 2009
Location: London, England
Posts: 1,907
Rep Power: 33
hjasak will become famous soon enough
Hi Mikko,

What you need is is called a movingWallVelocity boundary condition: this will make sure the velocity on the surface of the impeller (which MUST be in global Cartesian coordinates) is automatically updated to make sure the mass flux is exactly zero.

Looking forward to some updates + pretty pictures to show everybody what an open source effort can lead to.

Best,

Hrv
__________________
Hrvoje Jasak
Providing commercial FOAM/OpenFOAM and CFD Consulting: http://wikki.co.uk
hjasak 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
Superlinear speedup in OpenFOAM 13 msrinath80 OpenFOAM Running, Solving & CFD 18 March 3, 2015 06:36
64bitrhel5 OF installation instructions mirko OpenFOAM Installation 2 August 12, 2008 19:07
Adventure of fisrst openfoam installation on Ubuntu 710 jussi OpenFOAM Installation 0 April 24, 2008 15:25
OpenFOAM Debian packaging current status problems and TODOs oseen OpenFOAM Installation 9 August 26, 2007 14:50
OpenFOAM Training and Workshop Zagreb 2628Jan2006 hjasak OpenFOAM 1 February 2, 2006 22:07


All times are GMT -4. The time now is 14:55.