[arionfard]

Your cases are not working:

 --> FOAM FATAL IO ERROR: 
Unknown patchField type sixDoFRigidBodyDisplacement for patch type patch

Valid patchField types are :

30
(
angularOscillatingDisplacement
angularOscillatingVelocity
calculated
codedFixedValue
cyclic
cyclicACMI
cyclicAMI
cyclicSlip
empty
fixedNormalSlip
fixedValue
nonuniformTransformCyclic
oscillatingDisplacement
oscillatingVelocity
processor
processorCyclic
slip
solidBodyMotionDisplacement
surfaceDisplacement
surfaceSlipDisplacement
symmetry
symmetryPlane
timeVaryingMappedFixedValue
timeVaryingUniformFixedValue
uniformFixedValue
uniformInterpolatedDisplacement
value
waveDisplacement
wedge
zeroGradient
)


file: /home/behzad/OpenFOAM/behzad-2.3.1/run/freeOscillatingCylinder_scenario1/0/pointDisplacement.boundaryField.cylinder from line 26 to line 123.

    From function PointPatchField<Type>::New(const pointPatch&, const Field<Type>&, const dictionary&)
    in file /home/openfoam/OpenFOAM/OpenFOAM-2.3.1/src/OpenFOAM/lnInclude/pointPatchFieldNew.C at line 151.

FOAM exiting
------------------------------------------------------------------------------------------

Originally Posted by wyldckat

Greetings Maimouna,


Only at 3h00 from the end of 2014 was I able to finally look into this .

The only problem that scenario 2 had was the there was a small detail missing... I've rectified post #69:

            DontRotate
            {
                //Warning: Only valid where the predicted deviation from alignment is < 90 degrees.
                sixDoFRigidBodyMotionConstraint  fixedOrientation;
                tolerance       1e-06;
                relaxationFactor 0.7;
                fixedOrientationCoeffs
                {
                  //This is necessary, even if kept empty
                }
            }

Attached are the 3 scenarios. It looks like the 3rd scenario is more in accordance with the paper. The reason for this (which I'm guessing someone will eventually ask about this here on the forum) is as follows:

1. Scenario 1: has 4 springs with damping effects. This means that 4 forces are applied in all 4 springs, achieved by the spring effect and the damper will decelerate on all four springs. This results in the cylinder only being forced to move along X, because the forces along Y will balance things out and because the inlet flow is symmetric. Note: There is no rotation, because the fluid has pretty much no grip on the surface of the cylinder.
2. Scenario 2: by applying more constraints to scenario 1, the result is that the cylinder is constrained by opposing forces over Y which do not allow it to move along Y.
3. Scenario 3: S1 and S2 are springs and S3 and S4 are dampers. This means that the forces are not even on all directions, which has lead the cylinder to be more easily be pulled up by the S2 spring, leading to an oscillating behaviour over both X and Y. Again, no rotation occurs, because the fluid has pretty much no grip on the surface of the cylinder.

Best regards,
Bruno

[Maimouna]

Your cases are not working

Dear behzad,

try it in OpenFOAM-2.2.2 NOT 2.3.1. It seems to me, that is because of the released version in OpenFOAM you used.

All the best

[arionfard]

Originally Posted by Maimouna

Dear behzad,

try it in OpenFOAM-2.2.2 NOT 2.3.1. It seems to me, that is because of the released version in OpenFOAM you used.

All the best

No, the problem was the missing. So library! Ifixed it

[arionfard]

What kind of software is used for generating the .geo file in this case?!

[Maimouna]

I used Gmsh to generate the .geo file

[wyldckat]

Greetings to all!

@Maimouna: Following from post #80 and a recent private message you've sent me, here's what I can say in a short amount of time (last day on vacation today ):

Originally Posted by Maimouna

The topic that I would like to find out the results is the same topic that discussed before for rigid cylinder, but this time (Vortex-induced vibration of an elastic cylinder). In the elastic cylinder topic, I have to use the dynamic elastic equation which I think discussed in FSI library of OpenFOAM. For the elastic cylinder we should find displacements inside cylinder at all nodes. When I search about solving FSI problem using OpenFOAM, I could end up with using such FSI solvers in foam-extend-3.1. Because there are lots of structural solvers in that foam version. Take for example HronTurekFsi case in icoFsiElasticNonLinULSolidFoam solver in silidMechanics tutorial. I'm not sure if I right or not but that what I'm studying at the moment to understand icoFsiElasticNonLinULSolidFoam environment and then making some changes regarding my case.

OK, this is a much better description, although it didn't answer my question... but still, it's a positive step.

As for the topics you've sent me over private message:

In this topic, I would like to discuss both linear and nonlinear deformation. For linear (small) deformation, I would like to see how drag and lift forces affect cylinder. Here, I tried to follow the tutorial about flapping console given in the icoFsiFoam solver (after searching I ended up with that)

For nonlinear (finite or large) deformation, I would like to see how drag and lift forces affect cylinder. Here, I tried to follow HronTurekFsi tutorial which given in the icoFsiElasticNonLinULSolidFoam solver (after searching I ended up with that). Might I'm correct or not, I'm not sure.

Elastic cylinder is very sensitive to change it's shape during simulation because of the forces.

OK, you're roughly in the right direction of development, from what I can understand. I've mentioned this before several times, I think, but you should perhaps not go directly to trying and solving the issue with a cylinder. You should first make an even simpler test case, to ascertain how each FSI model works. The flapping console seems a good example to work with, for figuring out the limitations of each model, although I would prefer something even more simpler... but I can't think of anything right now.

Here, some points might help for implementing both case
1. for FSI, I need to solve two parts fluid and solid
a. fluid part: solve flow equation with velocity and pressure boundary conditions.
b. solid part: solve the elasticity equation with displacement boundary condition.

So far so good.

c. using Arbitrary Lagrangian- Eluerian (ALE) method for FSI.

I have no idea how ALE works, so I can't be of any help here

2. In the previous rigid case, the force which affects the cylinder is drag force which is coming from flow equation.

3. In FSI, we need to know how that drag forces from fluid affects the displacement in the solid surface, and how displacement affects on drag forces.

OK, so far so good...

4. In rigid case, drag force is equal for each point in the surface, but in FSI it is different for each point. (I'm not sure about this point, might I'm wrong)

AFAIK, the drag force we usually account for is the total over the whole exposed surface. We usually don't check how much force is applied on each particular point. You'll have to look for literature that has more information on how the "force profile" works along the surface of a cylinder or an air-foil.
Another detail is that you should check if you can achieve the same results when using a rigid cylinder with FSI interaction turned on; you should do not assume it gives the same exact results.

5. What to do to start? fix the cylinder center (displacement = 0).

Seems simple enough. You should be able to easily figure out how to do this, after all of the confusion we went through in this thread

I would like to make free case without springs and dampers, if possible, if not I'll going to add springs and dampers. I'm also bit confused, but following other tutorials such as flappingConsoleSmall in the same case solver, gives me idea about possibility to do it without spring and dampers (that is in foam-extend-3.1).

There are two possibilities that come to mind:

1. Either the cylinder's centre is firmly fixed;
2. Or the cylinder can travel along the channel... in which case... either you need a reaaaaally long channel, or use something like the particle accelerators, which use an O-ring shape or an 8 shape: http://en.wikipedia.org/wiki/Particle_accelerator

Best regards,
Bruno

[Maimouna]

Hi Bruno,

There are two possibilities that come to mind:

1. Either the cylinder's centre is firmly fixed;
2. Or the cylinder can travel along the channel... in which case... either you need a reaaaaally long channel, or use something like the particle accelerators, which use an O-ring shape or an 8 shape: http://en.wikipedia.org/wiki/Particle_accelerator

Since I didn't have the scientific published paper for such that case to say possibility 1 or 2, so let's take possibility 1 which is much more familiar to me.

I hope that explanation would be able to give you idea about what I'm trying to do.

Both cases linear and nonlinear elasticity deformation that I was trying referring to flappingConsoleSmal and HronTurekFsi in icoFsiFoam and icoFsiElasticNonLinULSolidFoam solvers, respectively, I'll post them within some minutes when back to my Ubuntu machine.

Kind regards

Maimouna

[Maimouna]

Hi Bruno,

the case about linear elasticity deformation was attached. And the second one for the large deformation elasticity will be attached in the next post because of its volume.

Kind regards

Maimouna

[Maimouna]

Still there is a problem with it's size, I unable to upload it. Any solution to solve this problem. Even I tried to delete some files, it's size is exceeded the 700 KB.

Any other way to upload my folder?

Regards

Maimouna

[wyldckat]

Originally Posted by Maimouna

Any other way to upload my folder?

Quoting myself from sometime ago:

Originally Posted by wyldckat

Quick answer: For files larger than 100kB, please use an external file sharing service. Here you can find a list: http://en.wikipedia.org/wiki/Compari...sting_services

Although Dropbox is the most commonly used/suggested here, although it's not the one that provides the most space for free.

[Maimouna]

Dear Bruno,

here is my case link
https://www.dropbox.com/sh/8cj7ligk1...xuMJGYkTa?dl=0

Regards

Maimouna

[Thaw Tar]

I have been working on 2D cylinder in VIV and could do the simulation. But I don't know how to record the motion trajectories (x-y trajectories) of the cylinder to compare with other published results (probably in paraview).

If anybody knows, please teach me. By the way, I am new to OpenFOAM.

[Maimouna]

Dear Thaw Tar,

you can record motion trajectory in pointDisplacement file or motionU file. I think that depends on the OF version that you are working.

Regards

[Thaw Tar]

Dear Maimouna,

Thank you. Actually, I am doing on OF 2.3.0 using 2.2.0 style dynamicMeshDict and pointDisplacement files.

I will try to take data.

Regards,
Thaw Tar

[Maimouna]

Dear Bruno,

here is the last case modification I did. I'm still couldn't figure out the problem

https://www.dropbox.com/s/cib2m83gqn...i1.tar.gz?dl=0

I hope you could. I changed the mesh and did some modification in the boundary conditions.

With lots of thanks and regards.

Maimouna

[Thaw Tar]

Dear Maimouna,

Actually, I want to extract x-y trajectories of only the cylinder patch from pointDisplacement files (the centre of mass of the cylinder). I am not interested about other points. Is there any method to do this?

If there are two cylinders, how should I get the centre of mass of these two cylinders over time?

If you have any information, please help me. I am totally lost.

Regards
Thaw Tar

[Maimouna]

Hi Thaw Tar,

if you would like to grep centre of mass, do the following
1. run the solver (i.e. pimpleDyMFoam) > log

2. all residuals will be saved in log file

3. OpenFOAM has a tool called ''foamLog'' which will scan an output file for certain things, and can customise it for your own requirement.

4. run foamLog log (where log is the name of the standard output file. Data will be written to another directory called ''logs''.

5. To get additional customised data you'll need to
i. creat a directory structure in home directory called .OpenFOAM/2.2.2 (where 2.2.2 is OpenFOAM version you are using. Please note that ''.'' at the front.

ii. copy the file OpenFOAM/OpenFOAM-2.2.2/bin/tools/foamLog.db to
. OpenFOAM/2.2.2

iii. add a line at the bottom of the newly created foamLog.db
com/Centre of mass: /Centre of mass: (
you should get x component, I'm not sure there is a way to get y component.

iv. run foamLog log to get ''com'' file in logs directory.

I hope that would help.

Regarding the centre of mass of two cylinders, I don't have any idea. I never work with two cylinders.

Kind regards

Maimouna

[Thaw Tar]

Thank you so much!

I will try!

Regards,
Thaw Tar

[Thaw Tar]

Dear Maimouna,

Thank you. I could extract centre of Mass data from log file.

By adding some awk commands, I could create a single centre of mass file for each cylinder.

However, I guess it might be much more tricky if the cylinder count gets higher.

Regards,
Thaw Tar

[jerikanti]

Hi,

I've taken a look at the forum and tried to run the files that were uploaded here. I managed to run the simulation using the same files in openFOAM 2.3.x (I made a small change on the dynamicMeshDict according to this thread: http://www.cfd-online.com/Forums/ope...f-2-3-0-a.html)

dynamicFvMesh      dynamicMotionSolverFvMesh;

motionSolverLibs (
			"libfvMotionSolvers.so"
			"libsixDoFRigidBodyMotion.so"
		);

solver            displacementLaplacian;

displacementLaplacianCoeffs
{
    diffusivity       inverseDistance (cylinder);
}

So here's my case:
1. For the mesh file, I used the blockMeshDict instead of the snappyHexMesh. The diameter of the cylinder is 0.5 m

2. I am testing it for Re=100

3. I want to see the VIV movement of the cylinder, so I tried to only enable the y-line motion

constraints
        {
        yLine
        	{
           	 sixDoFRigidBodyMotionConstraint line;
            	 centreOfRotation    (0 0 0);
            	 direction           (0 1 0);
        	}

4. I put 1 vertical spring above the cylinder, with no damping (I've seen post #69, but I just want to try this configuration first)

5. I use pimpleDyMFoam for the simulation

And here's the problem that I've had so far:
1. For this file: https://www.dropbox.com/sh/aqtu63hgb...29x2VCIla?dl=0
The cylinder does not oscillate at all even though the vortices are shed already

I made the configuration for the pointDisplacement file as follows

cylinder
    {
        type            sixDoFRigidBodyDisplacement;
        centreOfMass    (0 0 0);
        momentOfInertia (0.897 0.897 1.7448);
        mass            30;
        orientation
        (
            1 0 0
            0 1 0
            0 0 1
        );
        
        velocity        (0 0 0);
        acceleration    (0 0 0);
        angularMomentum (0 0 0);
        torque          (0 0 0);
        gravity         (0 -9.81 0);
        rhoName         rhoInf;
        rhoInf          1;
        report          on;

         restraints
        {
            S1
            {
                sixDoFRigidBodyMotionRestraint linearSpring;
                    anchor          (0 2 0); //A1
                    refAttachmentPt (0 0.25 0);
                    stiffness       0.5;
                    damping         0;
                    restLength      1.75;
            }
        }

        constraints
        {
        yLine
        	{
           	 sixDoFRigidBodyMotionConstraint line;
            	 centreOfRotation    (0 0 0);
            	 direction           (0 1 0);
        	}
        }        

        value           uniform (0 0 0);
    }

    back
    {
        type            empty;
    }

    front
    {
        type            empty;
    }

     ".*"
     {
         type            fixedValue;
         value           uniform (0 0 0);
     }
}

Could anyone help me to figure out what's wrong with this configuration?
Or perhaps is it because I am using OF 2.3.X ?

Regards,
jerikanti