[petr.f.]

I'd say there is FSI in the standard version - take a look at $FOAM_TUTORIALS//incompressible/pimpleDyMFoam/wingMotion/wingMotion2D_pimpleDyMFoam

... or do I get something wrong?

[wyldckat]

Greetings Petr,

Originally Posted by petr.f.

I'd say there is FSI in the standard version

FSI has a more broad approach, where it allows for solid shapes to deform depending on the interaction with fluids.
That particular tutorial only relies on a rigid-solid approach (it's named "sixDoFRigidBodyMotion" in "constant/dynamicMeshDict"), which means that even though the fluid may move the solid, said solid will not change its own shape.

The difficulty with FSI itself is usually with the solid deformation using an FVM (Finite Volume Method) approach, instead of the conventional FEM (Finite Element Method), as a reflex to the interaction of forces made by the fluid on the solid.

Best regards,
Bruno

[Maimouna]

Dear Bruno,

many thanks for your clarification.

I have question about my case. I already finished forced oscillation of circular cylinder (case attached). Now, I have been stuck in applying the natural vibration of my case. I tried to use wingMotion as a reference, but I didn't get the result. could you help me how to apply natural (free) vibration. I knew that I have to do some changes in pointDisplacement file referring to wingMotion test case. But unfortunately, I'm still stucking on that because I lake of information of different fields in pointDisplacement file in wingMotion folder.

Many thanks in advanced. Looking forward to get your answer.

Maimouna

[petr.f.]

Hi Bruno - that's what I've meant, just a simple case of FSI. Anyway - I haven't check the extend version, are they using FVM or FEM for structural deformations?

[wyldckat]

Greetings to all!

@Maimouna:

Originally Posted by Maimouna

could you help me how to apply natural (free) vibration. I knew that I have to do some changes in pointDisplacement file referring to wingMotion test case. But unfortunately, I'm still stucking on that because I lake of information of different fields in pointDisplacement file in wingMotion folder.

You'll have to be more specific on what exactly you want to do, because I can think of several kinds of natural vibrations for such a situation:

1. A natural vibration occurring in the fluid (ripple effect?).
2. The fluid inducing a natural vibration on the solid cylinder (force driven?).
3. Moving the cylinder at a previously known natural vibration frequency.
4. Structure deformation/destruction caused by reaching a natural vibration.

@Petr:

Originally Posted by petr.f.

Hi Bruno - that's what I've meant, just a simple case of FSI. Anyway - I haven't check the extend version, are they using FVM or FEM for structural deformations?

FSI stands for Fluid-Structure Interaction. It's briefly explained here: http://www.foamcfd.org/development.html

The "simple case of FSI" you're referring to would be Fluid-Solid Interaction... which is not the specific reason why the acronym "FSI" was created . More specifically, what you're referring to is usually addressed as dynamic meshing, as the changes that are made to the geometrical boundaries will enforce changes on the mesh, or vice versa.

According to the description on that page I gave the link above, the structure side is performed using FEM in foam-extend, which currently is no yet operational in the official OpenFOAM version.

Best regards,
Bruno

[Maimouna]

You'll have to be more specific on what exactly you want to do, because I can think of several kinds of natural vibrations for such a situation:

1. A natural vibration occurring in the fluid (ripple effect?).
2. The fluid inducing a natural vibration on the solid cylinder (force driven?).
3. Moving the cylinder at a previously known natural vibration frequency.
4. Structure deformation/destruction caused by reaching a natural vibration.

Dear Bruno,

I'm looking at case number 2, but this is not force. Any idea please?

Many thanks in advanced.

[karamiag]

Hi ok,
I downloaded your oscillating cylinder case, but I am not able to make the cylinder move. Could you please give more details about how to launch the case?
Thank you.

[Maimouna]

Hi ok,
I downloaded your oscillating cylinder case, but I am not able to make the cylinder move. Could you please give more details about how to launch the case?
Thank you.

Hi,

the cylinder oscillates properly in my OpenFOAM versions (2.2.2 and 2.3.0).

Which OF version do you use?

[karamiag]

I am using OpenFOAM version 2.3.0. In particular I have not found any information in your case about oscillation frequency or amplitude.

[Maimouna]

Strange
I just tried now to make sure. It's working. Did you use pimpleDyMFoam solver?

[karamiag]

This is what I have done.
tar xf oscillatingCylinder.tar.gz
cd oscillatingCylinder
blockMesh
pimpleDyMFoam
And this is what I obtain.

/*---------------------------------------------------------------------------*\
| ========= | |
| \\ / F ield | OpenFOAM: The Open Source CFD Toolbox |
| \\ / O peration | Version: 2.3.0 |
| \\ / A nd | Web: www.OpenFOAM.org |
| \\/ M anipulation | |
\*---------------------------------------------------------------------------*/
Build : 2.3.0
Exec : pimpleDyMFoam
Date : May 22 2014
Time : 19:44:06
Host : "ljjjjjkllkjl"
PID : 21970
Case : /home/tesisti/OpenFOAM/tesisti-2.3.0/run/oscillatingCylinder
nProcs : 1
sigFpe : Enabling floating point exception trapping (FOAM_SIGFPE).
fileModificationChecking : Monitoring run-time modified files using timeStampMaster
allowSystemOperations : Disallowing user-supplied system call operations

// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
Create time

Create mesh for time = 0

Selecting dynamicFvMesh staticFvMesh


--> FOAM FATAL IO ERROR:
keyword PIMPLE is undefined in dictionary "/home/tesisti/OpenFOAM/tesisti-2.3.0/run/oscillatingCylinder/system/fvSolution"

file: /home/tesisti/OpenFOAM/tesisti-2.3.0/run/oscillatingCylinder/system/fvSolution from line 23 to line 74.

From function dictionary::subDict(const word& keyword) const
in file db/dictionary/dictionary.C at line 643.

FOAM exiting

[Maimouna]

This is the steps:
1. Extract tar xf oscillatingCylinder.tar.gz
2. Copy and paste in pimpleDyMFoam solver in incomressible tutorial
3. In terminal window alias 'of230'
4. Go to the case path.
5. ./Allclean
6. ./Allprepare
7. pimpleDyMFoam
8. paraFoam

Hope this help.

Regards

[karamiag]

Extracting oscillatingCylinder.tar.gz I obtain a directory in which there is no Allclean or Allprepare file. Is it possible the targz file you uploaded is the wrong one?

[Maimouna]

Try this one. I hope it will help.

All the best

[karamiag]

OK, now it works!
Thank you.

[wyldckat]

Greetings to all!

@Maimouna:

Originally Posted by Maimouna

I'm looking at case number 2, but this is not force. Any idea please?

Sorry, time has been flying past me and only now did I manage to give a quick look into this. I see that you've continued to look into this and that you've found this thread: http://www.cfd-online.com/Forums/ope...tion-6dof.html

Essentially that thread does point in the right direction. My suggestion is that you also look into the tutorial case "multiphase/interDyMFoam/ras/floatingObject", comparing the versions on OpenFOAM 2.1, 2.2 and 2.3, because it has evolved over time. The idea in that case is that the floating body is moving due to impulsion of the fluid vs body density.

There is another example case... let's see if I can find it... ah, it's this thread: http://www.cfd-online.com/Forums/ope...opofvmesh.html - that example was for a sphere that was moving inside a tube towards a hole. The detail in this thread is that it uses a specific dynamic motion library, namely this one: https://github.com/smenon/dynamicTopoFvMesh

Best regards,
Bruno

[Maimouna]

Dear Bruno,

many thanks for your post. But, I'm still confusing how to implement that in the cylinder case. Have I create a new solver or my case? What is the exactly steps to get the result that I'm looking.

I'm really need some help. I lack of these technical steps.

Many thanks in advanced.

Maimouna

[Scabbard]

Originally Posted by Maimouna

Dear Bruno,

many thanks for your post. But, I'm still confusing how to implement that in the cylinder case. Have I create a new solver or my case? What is the exactly steps to get the result that I'm looking.

I'm really need some help. I lack of these technical steps.

Many thanks in advanced.

Maimouna

Hi Maimouna,

I have already make the case running use the sixDoFRigidBodyMotion solver, for me I looked at the WingMotions in the tutorials. For now, I just make it successfully run but have not make the validation of the result. If you need any help, may be I can help you with this case.

Scabbard

[Scabbard]

Originally Posted by wyldckat

Greetings to all!

@Maimouna:

Sorry, time has been flying past me and only now did I manage to give a quick look into this. I see that you've continued to look into this and that you've found this thread: http://www.cfd-online.com/Forums/ope...tion-6dof.html

Essentially that thread does point in the right direction. My suggestion is that you also look into the tutorial case "multiphase/interDyMFoam/ras/floatingObject", comparing the versions on OpenFOAM 2.1, 2.2 and 2.3, because it has evolved over time. The idea in that case is that the floating body is moving due to impulsion of the fluid vs body density.

There is another example case... let's see if I can find it... ah, it's this thread: http://www.cfd-online.com/Forums/ope...opofvmesh.html - that example was for a sphere that was moving inside a tube towards a hole. The detail in this thread is that it uses a specific dynamic motion library, namely this one: https://github.com/smenon/dynamicTopoFvMesh

Best regards,
Bruno

Dear Bruno,

Thanks for your keeping help. Now I want to record the trajectory of the cylinder's motion response, the centre of the cylinder displacement. Is there any function in the OpenFoam can do this? Thank you.

Best wishes,
Scabbard

[Maimouna]

Hi Maimouna,

I have already make the case running use the sixDoFRigidBodyMotion solver, for me I looked at the WingMotions in the tutorials. For now, I just make it successfully run but have not make the validation of the result. If you need any help, may be I can help you with this case.

Scabbard

Hi Scabbard,

of course, I need your help. I'm struggling on that for long time. If you don't mind please we can shear your idea and I would be really grateful.

My email address is: may78may@hotmail.com

Best regards
Maimouna