[fra76]

This is a good news!
However, I would like to implement something like "dynamicBodyFvMesh" with the new algorithm in OF 1.4...

[fra76]

Hi all!
In the OF 1.4 release notes, regarding mesh motion, I've found: "Flexible and efficient finite volume based mesh motion solvers (replacing the finite element mesh motion solvers)."
In another post inside this forum (http://www.cfd-online.com/cgi-bin/Op...how.cgi?1/4218) Hrvoje wrote "the cell-based diffusion equation which "replaces it" is so pathetically useless that I have abandoned it more than 10 years ago"

Can someone please explain me why the cell based method is so worse than the finite element one? Some article about both methods would help me a lot, too!

In one of my test cases, OF 1.3 fails, while the new method works better, and much faster, even if it slightly changes a fixed boundary. (Hrvoje, I think I could send you the pictures, if you're interested)

Bye
Francesco

[lr103476]

Just put the pictures here. I am also interested in the new car:-)

When Hrvoje manages to put all three (finite volume, cell decomp, cellFace decomp) into one 1.4 development release, I will make a comparison using a 3D moving body, looking at accuracy and efficiency.

Frank

[sek]

Hi Frank and others,

Can you please tell me how I can specify a dynamic pitching motion of an airfoil with 1.5? I see lots of discussion here but it's not clear whether I can do it without writing any code or not. -Thanks,

[lr103476]

Hi Sung-Eun Kim!

Do you want to describe the complete plunging pitching motion of the airfoil, or is there any fluid-structure interaction involved?

Regards, Frank

[sek]

Hi Frank,

Thanks a lot for your reply.

for now I have forced oscillation (prescribed motion) in mind. After posting the question, I somehow figured out from examples I could prescribe a translational and a rotational motion on the airfoil (both are periodic) using the dynamicBodyFvMesh class as shown below.

/*--------------------------------*- C++ -*----------------------------------*\
| ========= | |
| \ / F ield | OpenFOAM: The Open Source CFD Toolbox |
| \ / O peration | Version: 1.4 |
| \ / A nd | Web: http://www.openfoam.org |
| \/ M anipulation | |
\*---------------------------------------------------------------------------*/

FoamFile
{
version 2.0;
format ascii;
class dictionary;
object dynamicMeshDict;
}

// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
solverLib "libdynamicFvMesh.so";

dynamicFvMesh dynamicBodyFvMesh;

dynamicBodyFvMeshCoeffs
{
bodyPatchName movingWall;
translationDirection (0 1 0);
translationAmplitude 0;
translationFrequency 1;
initialRotationOrigin (0 0 0);
rotationAxis (0 0 1);
rotationAmplitude 0.349;
rotationFrequency 10;
}

twoDMotion yes;

solver laplaceFaceDecomposition;

diffusivity quadratic;

frozenDiffusion on;

distancePatches
(
movingWall
);

And in "U" file, I set the type as "movingWallVelocity". That's all I did. The solution seems what you would expect from a dynamically pitching airfoil. Did I miss something?

Thanks,
Sung-Eun

[lr103476]

Hi Sun-Eun,

This is exactly what I do for a complex flapping wing. In a dynamicFvMesh based class you can do whatever you like with the boundary points, so translation, rotation and/or flexing. DynamicBodyFvMesh is a class with only translation and rotating in one direction (if I am not mistaken), but you can easily extend that. Be aware that for large rotations the standard laplacian motion solver may not be good enough. In that case try the SBRStress motion solver, a small rewrite of your dynamicFvMesh class may be necessary......

Soon, we will put our Radial Basis Function motion solver in the SVN-dev repository.....

Enjoy the moving meshes!
Frank

[arashfluid]

Hi Frank and friends
I want to use icoFsiFoam in OF-1.6-ext to solve pitching and plunging motion of 3D wing problem. without FSI mode, I've applied those motions using two methods in dynamic MeshDict:1)solidBodyMotionFvMesh,2)dynamicMotionSo lverFvMesh with displacement Laplacian solver using pointDisplacement. But these methods and RBFmotion are based on finite volume,whereas icoFsi mesh motion is based on finite element.That's why I converet this solver to finite volume solver.The problem is that after running the solver,wingsolid and wingfluid,each of them moves separately and do not affect each other.
would you please tell me how I could do it with the previous finite element solver?Like the flapping console test case, with knowing the difference between these two cases, that here the plunging motion should also be applied to solid.

[maryfery]

it is used to be possible to do it in OF 1.6 via dynamicBodyFvMotion class but this class does not exist in 2.3 version.
also I tried to use SBRStress but i don't know how to implement the prescribed motion.
I need a function like tabulated6DoFMotionCoeffs which reads the translations and rotations from a .dat file for example.
thanks for your response in advance.

cheers;
maryam

[fsifsi]

Hello Francesco Del Citto
Could you post your dynamicMeshDict again, please.
I get error "Selected mesh motion solver is RBFMotionSolver, instead tetMotionSolver"
when i use dynamicBodyFvMesh in OF3.1.ext
Many thanks

Originally Posted by fra76

Thanks Frank!
My mistake was using "moveMesh" instead of "moveDynamicMesh".
I can rotate the cube, at last, and I know what I have to modify in order to add mya own motion laws.
I'll play a bit with this, and I'll let you know if I'll be able to move a subset within another one.

Ciao
Francesco