[Nigò]

I will be glad to do it, can you please give us some references to the cases and results that are you talking ?
I've done some search but I haven't found nothing.

Thank you in advance.

[wyldckat]

Quick answer: In regards to this:

Originally Posted by hjasak

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

The aforementioned cases are probably the ones available at one or both of the following repositories:

• In the "nextRelease" branch at the main foam-extend 3.2 repository: https://sourceforge.net/p/foam-exten...tRelease/tree/
• At Hrvoje's personal fork of foam-extend 3.2, where he prepares his commits to be later merged into the main repository: https://sourceforge.net/u/hjasak/foam-extend-3.2/

[crixman]

Hi everybody,
I am making some basic benchmarks of the IBM method.
I tried a simple laminar Hagen-Poseuille flow and the mass velocity of the flow is not exactly correct (20m/s analytical vs 17.5m/s from the simulation) and convergence after about 1000 iterations.
I cannot understand the problem, if someone is interested I can post the case.
Let me know,
Christian

[RobertG]

Dear Prof. Hrvoje Jasak,
I would like to thank you, for all the effort you made by implementing the immersed boundary methode.
At the moment I'm using them more or less succesfully. I designed a 2D testcase, on which every thing worked fine.
But when I used it with a more complex meshshape in 3D, I discovered a some problems.

I managed to solve a couple of them and would like to publish their solution and discuss the problems, I did not manage to solve.

Solved problems are:
- immersedBoundaryFvPatch.C:
Running potentialIbFoam in parallel, it is possible that because of the different proceses are different fast. Which causes at some points a difference of more then 2 sec at the position of the programm on the different processes. Because of this delay, it is possible that a process freezes when it demands a value of another process, bevore it was send.
I solved it, by using MPI_Barrier( MPI_COMM_WORLD ); to synchronize the processes. It is neccessery to use this, before every up and download of a value (OPstream, IPstream and sendAndReceive(...)/immersedBoundaryFvPatchField.C)

- immersedBoundaryFvPatch.C:
cellProcCells[cellI].setSize(100) is at some cases to small and causes the potentialIbFoam to crush.
I would recommend resetting the size dynamicly if it is necessary.


Problems I was not able to solve.
- void immersedBoundaryFvPatchField<Type>::write(Ostream& os) const
It takes a lot of time to do U.write() (or so I belive. Once I waited 12 h for it, but it was not finished)
triValue() was calculated pretty fast, so I don't know what happens after it. Seriously, I have no clue what causes the extreme long run-time.
But I have one recommandation for improving the speed (if it would work regulary). If the writing-procedure is serialized, so that only one process writes at a time (It might improve the writing procedure when a hard drive is used).

When I use the potentialIbFoam in serial, it works fine. Non of the noticed problems to be seen.
But if I run decomposePar after it, it takes about one week to decompose the case.
This might be related to the last mentioned writing-problem.
But unfortunatelly, I don't finde every related class in this matter.

I hope you or somebody else can help me in this matter and give me a clue, how solve the last mentioned problem or give me a hint, in which classes are related to this problem.

Best Regards
RobertG

[hjasak]

Hi Robert,

Thank you for looking into this. Can you please send me the files you have changed to review the bug fixes and merge them in.

I am looking into the best way to rewrite the parallel communications in the Immersed Boundary to make everything faster, but this is a bigger project so it will require real funding. The comms we have now are fine for a smaller number of processors, but as the decomposition increases, the code will become inefficient. I will speak to Zeljko to see what we should do; however, some significant funding is required to get this fixed.

Regarding the writing of U and other fields: at this point in the code, the data from the IB points is interpolated into the points of the STL surface. The algorithm I am using is a surface walk, which is linear if the STL is clean and does not protrude outside of the background mesh. Ideally, the resolution of the STL surface should be comparable with the resolution of the background mesh.

I assume you found a case where the surface walk algorithm fails, eg. if the STL is folded over or similarly broken.

Hrv

[afrotimy]

Originally Posted by Phicau

Hi Hua,

this error rings a bell to me:

[pjh-Veriton-D832:8321] *** An error occurred in MPI_Recv
[pjh-Veriton-D832:8321] *** on communicator MPI_COMM_WORLD
[pjh-Veriton-D832:8321] *** MPI_ERR_TRUNCATE: message truncated
[pjh-Veriton-D832:8321] *** MPI_ERRORS_ARE_FATAL: your MPI job will now abort

It was also triggered by a parallel boundary condition I developed. The solution was found thanks to Bernhard:

Edit $WM_PROJECT_DIR/etc/controlDict and change commsType to nonBlocking .

You should try and see if this helps with your problem.

Best,

Pablo

Hi foamers,

I can see that this thread has been for a long time.

I just want to know if anyone has been able to run icoIbFoam or icoIbDyMFoam in parallel in foam-extent-3.2.

I have the decomposeParDict correctly specified and ran well for other solvers, but when running the IB solver, it gives error messages are quits as it have been reported.

I tried to change the commsType to unblocking, problem still not resolved.

I noted that in foam-extend-3.2, the etc/controlDict was kept as etc/controlDict-Example. Although, I don't know why but I copied it as etc/controlDict.

Any suggestion would be appreciated.

[supersoldier]

I use openfoam-extend-3.2 version for studying the problem of IB. I have successfully run the case cavity which is from https://github.com/wyldckat/Immersed.../cavity/cavity.

I create a new case myself which is also a lid driven cavity, but twice height than before. I create a stl file, which is shown in left picture below in blue. When I run this case, I found the immersed boundary is not work.


I study the case and immersed boundary setting again, I find that the stl surface may be need closed. So I create another stl file. This time the IB works well.


I add a temperature equation in the solver icoIbFoam, I want to simulate the case like the conjugate heat transfer problem, the upper is fluid and the bottm part is solid , the heat is transfer from the fluid to the solid.


But after run the case I get confused myself about the immersed boundary :

The first is if the immersed boundary now implemented in OpenFoam-extend3.2 can handle the the multiregion problem, such as heat transfer between two regions? I think maybe now the IB just act as a wall boundary is that correct?

The second is if the stl surface need closed. Becase I want to add cyclic boundary for the left and right side of the rectangle, if the stl surface need closed, the solid part boundary will all be IB!

I am doing some work about solid materials combustion, so if you can give me some advices , I will really appreciate it. Thank you.

[Engineers]

Dear all,

I'm tasked with the following problem, but I'm not sure if I can get it done using just the IcoIbFoam as requested. Here is the problem, we need to simulate flow around a flexible finite aspect ratio flat plate positioned normal to the incoming flow using IBM. The idea is that the plate would deform under loadings due to the vortex shedding, and we need to capture how the wake transforms due to these deformations. I've read in various places here how the FSI solver accommodates flexible elastic walls, pipes, etc. However, I am not sure if the FSI can be incorporated into the IBM solver (IcoIbFoam). What are your thoughts on this?

This is what we have already done: we have simulated the flow around a rigid stationary finite aspect ratio using IcoIbFoam. We have also simulated the flow around a rigid and pitching plate using IcoIbFoam.

Thanks a ton

AH

[sina_mech]

Hi All! I am new to immersed boundary in foam-ext 3.2 and have a basic question!

How do you create STL files?!! I create them using Rhinoceros, and make a before exporting them as SLT. Is that a right way? (please check the attached stl file for an example)

My other question is that how we determine the spacing between the points of the immersed boundary? Does it even matter for the current solver?

Sorry if the questions are so trivial! a newbie here

Thank you in advance!

[sina_mech]

Originally Posted by sina_mech

Hi All! I am new to immersed boundary in foam-ext 3.2 and have a basic question!

How do you create STL files?!! I create them using Rhinoceros, and make a before exporting them as SLT. Is that a right way? (please check the attached stl file for an example)

My other question is that how we determine the spacing between the points of the immersed boundary? Does it even matter for the current solver?

Sorry if the questions are so trivial! a newbie here

Thank you in advance!

Dear Prof. Hrvoje Jasak,

In addition to questions above, I have another question, and I would really appreciate if you could kindly advise me about these questions.

In the presentation files, it's mentioned that we can refine the volume mesh.
do we need to refine the IB boundary as well? and if yes, how can I do that?

I could edit the existing code to refine the volume mesh, but still have problem for flow around a cylinder, and I think it might be because of IB file. This is the error I get

Starting time loop

Time = 0.01



--> FOAM FATAL ERROR:
allPoints.size() < 5 : 4

    From function void immersedBoundaryFvPatch::makeInvDirichletMatrices()
    in file immersedBoundaryFvPatch/immersedBoundaryFvPatchLeastSquaresFit.C at line 95.

FOAM aborting

Thank you very much
Sina

[dmsg]

Hello everyone. I'm pretty new to this forum and I'm new to IBM in OpenFOAM. I am having issues installing open foam-3.1-ext with my existing OpenFOAM installs (v3.0.1). Has anyone experienced this before?

I attached the output from ./Allwmake

[Phil_]

Hi foamers,

does anyone have a clue why 'sampling points' are used in the IBM, especially in the context of turbulence modelling with wall functions?

Best Regards
Philip

[hjasak]

Hi,

Think about how the immersed boundary works. Having the IB fit in the wall function cell would be impossible if you do not know y+ - and this data cannot be taken out of the IB fitting itself because it is unstable.

I found an original paper from Standofrd doing this on a structured mesh (badly) and I developed + implemented the idea further. There should be papers describing this, eg ECCOMAS.

Hope this helps,

Hrv

[syavash]

Hi,

I do LES on version 2.3 and I was wondering if it is possible in extended version to perform LES using IBM?! I mean does a pimpleIbFoam-like solver exist? or is it doable to develop such a solver just like simpleIbFoam has been devlopped?!

Thanks,
Syavash

P.S: I am trying to use LES on a rough surface with a body-fitted mesh but I am not sure it is the best idea because the mesh (especially aspect ratio) is not a typical LES mesh due to surface roughness

[saeed_hb]

Hello
I am modeling an airfoil with icoDyMIbFoam and I want to get the pressure distribution over the airfoil, in fact I want to know the pressure on ib surface ... how can I do that? is there any function like sampleDict for Ib surfaces?? The ib boundary is not real, since it has mapped in the background mesh so I have not any real boundary that can be used in sampleDict as a boundary.... this is the problem here

Thanks

[hjasak]

See foam-extend-4.0/src/immersedBoundary/immersedBoundaryForce

There are function objects for this.

[saeed_hb]

Is there any way that immersed boundary method can be used for fluid structure interaction problems in foam-extend-4.0?

[Ben UWIHANGANYE]

Hello Dear Foamers,

Please help to do tutorials of IB in OpenFoam
- Cylinder in a Cavity
1. How to Define volume mesh in constant/polyMesh/blockMeshDict dictionary?
2. How to Create polyMesh using blockMesh?

3. how to Include immersedBoundaryPolyPatch into polyMesh boundary.

4. How to Include immersedBoundaryFvPatchField into boundary field of pressure and velocity fields.

Through which way, i can make this?
and I have tried to run IcoIbFoam but said that such command doesn't exist

Thank you!

[RobertG]

Originally Posted by Ben UWIHANGANYE

Hello Dear Foamers,

Please help to do tutorials of IB in OpenFoam
- Cylinder in a Cavity
1. How to Define volume mesh in constant/polyMesh/blockMeshDict dictionary?
2. How to Create polyMesh using blockMesh?

3. how to Include immersedBoundaryPolyPatch into polyMesh boundary.

4. How to Include immersedBoundaryFvPatchField into boundary field of pressure and velocity fields.

Through which way, i can make this?
and I have tried to run IcoIbFoam but said that such command doesn't exist

Thank you!

Hello Ben,
thous are very basic question.
Tharefore, I whould suggest, you should have a loock at,
https://www.openfoam.com/documentati.../blockMesh.php
This will provide a answer for question 1.+2.

regarding 3.+4.
may be you should habe a look at the tutorials you can find in:
foam-extend-4.0/tutorials/immersedBoundary

If want to you use immersedBoundary, you should use foam-extend-4.0

There are 3 reasons why icoIbFoam whount start.
1. Immersed Boundaries are officialy available since foam-extend-3.2
2. You did not compile foram-extend-3.2 or 4.0 correctly.
3. You did not start the script foram-extend-X.X/etc/bashrc
(4. You are not using foam-extend at all)

Best Regards
RobertG

[fireztw]

Originally Posted by RobertG

Hello Ben,
thous are very basic question.
Tharefore, I whould suggest, you should have a loock at,
https://www.openfoam.com/documentati.../blockMesh.php
This will provide a answer for question 1.+2.

regarding 3.+4.
may be you should habe a look at the tutorials you can find in:
foam-extend-4.0/tutorials/immersedBoundary

If want to you use immersedBoundary, you should use foam-extend-4.0

There are 3 reasons why icoIbFoam whount start.
1. Immersed Boundaries are officialy available since foam-extend-3.2
2. You did not compile foram-extend-3.2 or 4.0 correctly.
3. You did not start the script foram-extend-X.X/etc/bashrc
(4. You are not using foam-extend at all)

Best Regards
RobertG

Hello RobertG,
As a beginner of IBM in OF like Ben, I have run some tutorials in OF-ex3.2 and changed the mesh/IB(.stl) by my needs. But i can't understand the specific processing methods(eg: solver etc.),following questions:
1. What changes are there in the Ib solver compared with original (eg: icoFoam to icoIbFoam)
2. I want to use my own algorithm to solve relevant problems, what files are need to understanding and make changes.

Best Regards
fireztw