Hi Mr. Naimul Haque,

I'm sorry for the late answer.
I tried to use the fixedPlane option and it seems that it constrains a point that is in a plane to stay in that plane.
That means that if roll movement has to be fixed (rotation around x axis -1 0 0-), the plane whose normal is (0 1 0) has to be fixed. In such a way the only movement will be pitch (around y axis) because it won't be possible to have yaw (this movement will move a point in xz plane out from this plane).
Do you agree??

What do you mean with dealing with the constrain tensor? I still haven't faced any problem like that

regards

Luca

hi people
i am new to openfoam can anyone tell me what should be the entries in pointdisplacement file so i i get a free rotational and translation motion ie: full six dof motion

Dear Luca Bonfiglio,

Sorry, I just have seen your post, long time I am not using. I have forgot. Now I am running static cases. After finishing static cases, I would start dynamics cases. Hope I can help you on that time.

Dear Flash,

I forgot, long time I am not using. Sorry. If I can remember something, I would let you know.

RBF vs 6DOF
 

Hi
I've used the RBFmotion for my flapping airfoil (rotation and translation). But the running time was too long.(50 days with 40000 cells).That's why I decided to use the sixDofRigidBodyDisplacement.But I am not familiar with its parameters.
Does anyone have a pdf about it?How do I apply two degrees of freedom for airfoil?Is there a connection between the RBF and sixDof?

wingmotion
 

Take a look at he pimpleDyMFoam tutorial called wingmotion.

sixdofrigidbodydisplacement
 

Dear foam users,hi
i am simulating the flow around a rotating cylinder with sinusoidal translation simulantaneously...
I need a good bounadry condition such as "sixdofrigidbodydisplacement" but i can not use it,because of complexity :(
can anyone help me please?:)

Dear arash, please help me to use RBFmotion solver...

RBF motion
 

mr sattari
You should refer to: http://repository.tudelft.nl/assets/...daa1b2/bos.pdf

sixdofrigidbody
 

Hi Foamers,

I want to simulate the flow around a ship-model with free trim (rotation around y-axis) and heave (translation in z-axis-direction) with interdymfoam.

My grid represent the dynamic position of the ship, so the model is in a given trim- and heave-position.

Makes it sense to fix all dof until there will be a full developed flow and after that unfix the motion around y-axis and in z-axis-direction. If yes, how i fix all dof? With over-constraining?

Or is it a better way to start the simulation directly with free trim- and heave-motion?

Thanks for help.

Regards

Conrad

sixDoFRigidBodyMotion for multiple bodies
 

Hi All,

I have a question on linearSpring restraint in sixDoFRigidBodyMotionRestraint
when the anchor is on another moving body. For example in the default linearSpring.C the r vector is calculated as :

vector r = restraintPosition - anchor_; // anchor is fixed.

How can this code be modified such that anchor is on another moving body? In other words, how can the sixDoFRigidBodyMotionRestraint class be modified to acquire the, say the centreOfMass of another floating body.

Thanks in advance

Kumar

Dear Kumar,

did you find answer for your question?

I'm working in free vibrating cylinder and I'm struggling in pointDisplacement file. I'm still looking for answers of some questions for using sixDoFRigidBodyDisplacement. If you could help me that would be grateful.

Kind regards

Maimouna

Hi Maimouna,

At this point there is no way to do this , i.e, make one body recognize center of mass etc of another body. You need to rewrite the forces library extensively to do this. Sorry I cannot be of much help here.

Regards

Kumar

Hi foamers,

I would like to know what constrains should I put if I need free motion in all 6 direction??

Thanks

Hi Kumar:
In the waves2Foam topics, you added the density term into the turbulence model for simulation wave breaking. I want to research the undertow under the spill breadking wave. when simulatiom i have found that the wave elevation decay. so I think it's because the density term is not included in the turbulence model, and i don't know how to added the density term into the turbulence, can you help me? Thanks.
best regards
Fanfei

I need help in specifying fixedPlane constraint in dynamicMeshDict for a 2D case in the x-y plane with pitching motion and translation in x and y

Is this entry the correct way

fixedPlaneXY
{
sixDoFRigidBodyMotionConstraint fixedPlane;

fixedPlaneCoeffs
{
refPoint $centreOfMass;
direction (0 0 1); //normal direction to plane
}
}

I am solving an overset mesh problem and use the sixDOFMotion to slide one mesh over the other. I need to constraint the motion in the x-y plane.

And using fixedAxis seems to not update my rotation as the axis vector (0 0 1) does not lie in my moving mesh.

Thank you

Userdefined restraintForce in linearSpring
 

P { margin-bottom: 0.08in; } Dear All,


I am trying to create a “userdefined.so” for defining the 'sixDoFRigidBodyMotionRestraint' condition, by modifying the file 'linearSpring.C'. In the file it shows that the value 'restraintForce' is calculated. I would like to read the value for 'restraintForce' from an input file.
Can this be done by using #include option?
What is the input file format for that and how to assign the value read from the input file to restraintForce. Your suggestions and guidance will be highly helpful. Thank you


Most&More
Gautami Erukulla.

You can achieve that by not including any constraints.

Dear Gautami,

Did you manage to change the restraintForce in linearSpring.C file? If yes, please share how did you do that. I am actually looking to modify the restraintForce equation by adding the external force, but haven't succeeded yet.
Thanks.

Best,
Sachin

Dear Sachin,

I found the following paper,

http://www.tfd.chalmers.se/~hani/kur...JP_peered1.pdf

wherein the details to modify the restraint force in linearSpring.C file are explained with an example. I worked accordingly and was able to modify with out issues. I am hoping this paper would be useful for you too and works out.Thanks.

Most&More,
Gautami Erukulla.