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[ImmersedBoundary] Immersed Boundary Method in OpenFOAM-3.1-ext

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Old   August 30, 2015, 00:56
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Dear Prof Hrvoje Jasak,

Thank you very much for your reply. In foam extend-3.2, the cylBumpInterIbFoam tutorial runs without any problem. But if I refine the ibCylinder for level 3 using refineImmersedBoundaryMesh -ibCellCellFaces the solver show all.points < 5: 2 , If I use level 4 refinement it end up with singular matrix error, If I refine ibCylinder region using mesh refinement options the courant number diverges after 0.10 sec. I am wondering about refinement technique which can be used for immersed body. Actually I want use immersed boundary method (as overset is not available in public release) for dynamic body simulation in waves.

Best Regards,

Ali
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Old   October 8, 2015, 04:18
Default Rotating ImmersedBoundaries
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Robert Grandl
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Hy,
I'm trying to make the ImmersedBoundaries move.
I already had a look in to the source code.
Unfortunately, I did not understand it realy good.
Can someone tell me, which file or where I can find the code, which is resposible to read the .stl-files.

It whould be realy nice, if some one can give me a short overview ouver the programm structures of immersed boundaries.

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RobertG.
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Old   October 8, 2015, 06:41
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Hi Robert,

I looked into this too but couldn't find a proper solution yet.

If you "just" want to move the IB but not alter the body-shape you can take a look at the movePoints() / moveTriSurfacePoints() method in immersedBoundaryPolyPatch.C. It should be possible to move the already existing IB-points. (I think this happens via dynamicMesh handling.)

If you want to alter the IB-body-shape altogether it's getting complicated. I have not been able to read in a new .stl/.ftr during runtime. If someone has a clue how to do that, please respond

Best regards,
Philip

Last edited by Phil_; October 8, 2015 at 08:26.
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Old   October 8, 2015, 07:54
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Have a look in 3.2 nextRelease branch: I made a dynamic mesh class and a tutorial for a moving immersed boundary.

Enou
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Old   October 8, 2015, 11:01
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Hello Philip and Prof. Hrvoje Jasak,
thanks a lot for your fast replay.
I want to simulate an twin screw extruder.
Therefore, I have two rotating parts.
But I want to couple the CFD-Simulation with an DEM-Simulation, using foam-extendet, LIGGGHTS and CFDEM.
So, I have to create my own solver, based on the cfdemSolverPisoScalar.

Is it possible?

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RobertG.
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Old   October 8, 2015, 11:18
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I don't think you can do a screw extruder with immersed boundary. Tolerances in the gap are just too fine and the flow is critically dependent on the resolution in gaps.

At Wikki we have done projects with screw equipment using custom mesh motion. This is probably some of the most beautiful and challenging moving mesh cases I have seen or done Not easy, though.

Doing this through Wikki would require funding and an industrial partner; you are most welcome to try IBM or alternative dynamic mesh, but be advised: this is not easy!

Hrv
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Old   October 8, 2015, 12:31
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Hello Prof. Hrvoje Jasak,
I'm sorry, I used, the term twin screw extruder, because, it is more common.
In fakt it is more than a co-rotating twin screw mixing reactor.
The rotation-zylinder of both screw are overlapping, which is the reason, why I can't use the dynamic meshing.
But, between the two screw is always enough space.
Thanks a lot for your help.

Best regards
RobertG
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Old   October 8, 2015, 14:24
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Dear Prof. Hrvoje Jasak

I am trying the analyze the vortex formation / stability etc. at a flapping / heaving fin. Therefore the I'd like to use the immersed boundary method.

As you mentioned you've made a dynamic mesh class and a tutorial for the immersed boundary method. Unfortunately we cannot find it. All of the tutorials of the immersed boundary of the version 3.2 extended (http://sourceforge.net/p/openfoam-ex.../ci/v3.2/tree/) are static.

Are we missing something?

Thanks for the help
Daniel
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Old   October 8, 2015, 14:49
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Dear Prof. Hrvoje Jasak,
just now, i tried to download the newes version fe32.
When I open the Link at the browser, I see, that there are tutorials for IB.
However there are missing, when I download fe32 via the given git command/url.
But using the "Download Snapshot"-Button works fine ?!

Thanks a lot for the support and your work.

Best regards
RobertG
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Old   October 8, 2015, 19:47
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Quoting myself from a few minutes ago:
Quote:
Originally Posted by wyldckat View Post
Actually, he was referring to his own repository: http://sourceforge.net/u/hjasak/foam...tRelease/tree/

If you want to start with a new clean copy, you can get it with the following commands:
Code:
git clone git://git.code.sf.net/u/hjasak/foam-extend-3.2 foam-extend-3.2
cd foam-extend-3.2
git checkout nextRelease
If you want to use your already existing repository of foam-extend 3.2, then use these commands:
Code:
foam
git remote add hjasak git://git.code.sf.net/u/hjasak/foam-extend-3.2 
git fetch hjasak
git merge hjasak/nextRelease
The tutorial folder is this one:
Code:
tutorials/immersedBoundary/movingCylinderInChannelIco
The new solver is this one:
Code:
applications/solvers/immersedBoundary/icoDyMIbFoam
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Old   October 9, 2015, 04:13
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Dear Prof. Hrvoje Jasak,

is it already possible to vary the geometry of the immersed body over time? In the tutorial case the cylinder moves but there's no change in shape.

Best regards
Philip
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Old   October 9, 2015, 10:31
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Bruno

Thank you very much for the link. However something is wrong with the dynamic mesh file.
In my case it contains just a "+" at the top and the next ca. 850 lines are empty, which makes no sense to me. The same thing holds true if I try to download it directly by your posted link.

Thanks
Daniel
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Old   October 10, 2015, 06:49
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I've tested it now. There are a few glitches in his repository. For the fixes, see post #11 in this thread: http://www.cfd-online.com/Forums/ope...tml#post567429

edit: For questions and issues about the Dynamic Meshing with Immersed Boundary Method, please use the dedicated thread: http://www.cfd-online.com/Forums/ope...hannelico.html

Last edited by wyldckat; November 7, 2015 at 13:47. Reason: see "edit:"
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Old   January 21, 2016, 05:24
Default Potential Flow
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Dear all,

has anyone noticed the potentialIbFoam not working as expected?

Please see the attached pic showing the streamlines of the potential solution
for a pitzDaily.

Is this known? Is there already a fix available? Or am I doing something wrong?

Best regards,
Philip
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Old   January 21, 2016, 05:39
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The mentioned behaviour can be noticed in turbulent cases, e.g.

tutorials/immersedBoundary/backwardStepShortTurbulentSimpleIbFoam
tutorials/immersedBoundary/pitzDailyTurbulentSimpleIbFoam
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Old   January 21, 2016, 08:06
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Quote:
Originally Posted by singhfme View Post
Has foam-extend-3.2 been released?
jup.
https://openfoamwiki.net/index.php/I...oam-extend-3.2
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Old   January 29, 2016, 03:39
Default Turbulent IBM behaviour
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Dear all,

for a fully developed 2D channel flow at Re=25.000 calculated with k-epsilon turbulence model I get quite different results with simpleIbFoam compared to simpleFoam.

Can anyone confirm this?

Best regards,
Philip
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Old   February 2, 2016, 09:32
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Hello,
I have created a new solver, which uses ImmersedBoundarys which are provided at foamExtend 3.2 .
Unfortunately, I don't need the ImmersedBoundarys at all boundary condition.
In dead, it causes at one point an Error in combination with an volScalarField boundary Condition.
Is ist possible to swicht of the ImmersedBoundarys, at boundary condition at which Ib are not neccesery for a correct calculation?

Thanks a lot.

Best regards
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Old   March 4, 2016, 09:52
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Hi foamers,
I'm trying to validate the new Immersed Boundary solvers in the foam extended version 3.2.
For the first case I've tryed the classic 2D cylinder at Reynolds =100.
The body fitted simulation work fine, but with the IB I get some strange results.

In fact the viscous Lift have a mean different to zero (see the attachments), but looking at the averaged time fields the wake is still simmetric to the cylinder axis, so I think that some mistakes are presents in the force calculation functionObject.

Is someone experienced the same problems ??
Have you any guess to how correct the problem ?

Thank you in advance, Nigo
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Old   March 4, 2016, 11:00
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We have published laminar and turbulent flow validation results at ERCOFTAC last year and did a validation study on a moving immersed boundary this December.

Why don't you start from those cases and find out where you made q mistake. All validation cases are public
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