[liuyang]

Hi former:
I used version 1.5 for flow around oscillating cylinder,but it seems that two files:
cellMotionU and pointMotionU.
I used a file pointMotionU like this:
dimensions [0 1 -1 0 0 0 0];

internalField uniform (0 0 0);

boundaryField
{
cylinder
{
type oscillatingVelocity;
omega 0.1;
amplitude (0 -0.628318531 0);
value uniform (0 0 0);
}
up
{
type fixedValue;
value uniform (0 0 0);
}
down
{
type fixedValue;
value uniform (0 0 0);
}
inlet
{
type fixedValue;
value uniform (0 0 0);
}
outlet
{
type fixedValue;
value uniform (0 0 0);
}
frontAndBackPlanes
{
type empty;
}
}
and the same for cellMotionU. There seems to be something wrong, the error message is:
gradientInternalCoeffs cannot be called for a genericFvPatchField (actual type oscillatingVelocity)
on patch cylinder of field cellMotionU in file "/home/ly/OpenFOAM/ly-1.5/run/os_cyclinder/0/cellMotionU"
You are probably trying to solve for a field with a generic boundary condition.

Then what should the file cellMotionU should look like?
Thanks a lot.

[mathieu]

Hi,

I think removing the cellMotionU file from the "0" directory will solve the problem.

Mathieu

[liuyang]

Hi:
Following your instruction,it works now.Thank you very much.

LiuYang

[patriem]

Hello,

for an oscillating sine motion with vel_amp_x=0.226m/s and frequency of 128Hz i used oscillatingVelocity and a pointMotionU with


type oscillatingVelocity;
omega 804.096; //=2*pi*f
amplitude (0.226 0 0);
value uniform (0 0 0);

But the oscillating amplitude seems to be much too high. what do i do wrong? The oscill....C file under fvMotionSolver/pointPatchFields/derived/oscillatingVelocity
is standard with
(p0_ + amplitude_*sin(omega_*t.value()) - p.localPoints())
/t.deltaT().value()
);

Thank you for a hint

[ssp]

Patrick,

You need oscillatingDisplacement and not oscillatingVelocity. Are you using OF 1.5? Have you had any problem with oscillatingFixedValue?

Sopheak

[patriem]

Hello,

I don´t think that i MUST use oscillatingDisplacemt. I can also describe the motion by oscillatiingVelocity, with the maximum value of velocity as the amplitude, and omega as 2*pi*f.

I want to use it for pointMotionU, the inputfile for velocitylaplacian (dynamic mesh). The oscillatingFixedValue b.c. is not supported here, so i need oscillatingVelocity.

COuld you tell me the correct entries and meanings for omega and value uniform? By the way, what is p0?

[patriem]

can´t anybody help me? tried it again today, but the meshmotions isn´t the expected. the amplitude is much too high!

[ssp]

Patrick,

Try to use oscillatingDisplacemt on the velocity field and you will be suprise. Just change oscillatingVelocity to oscillatingDisplacemt.

Sopheak

[ssp]

like this:

type oscillatingDisplacement;
omega 804.096; //=2*pi*f
amplitude (0.226 0 0);
value uniform (0 0 0);

[patriem]

Thank you very much, i am one step further right now!

I could change the sin to a cos-motion by editing the oscillatingDisplacement...C file. And it still works.

Patrick

[patriem]

I have to mention that there were of course changes in the dynamicmeshdict (to displacementlaplacian)
fvsolution and fvschemes necessary. and the file in 0 should be called pointDisplacement.

[pedrampakzad2006]

which changes should have for
(fvsolution and fvschemes)?!?
please help me!!

[desmoge]

Prolly he refers to the fact that you have to specify a solver for 'cellDisplacement' in fvSolution and a scheme for the diffusivity under 'laplacianSchemes' in fvSchemes.
I personally use 'PCG' for the first and 'Gauss linear corrected' for the second.
Bye

[pedrampakzad2006]

Originally Posted by desmoge

Prolly he refers to the fact that you have to specify a solver for 'cellDisplacement' in fvSolution and a scheme for the diffusivity under 'laplacianSchemes' in fvSchemes.
I personally use 'PCG' for the first and 'Gauss linear corrected' for the second.
Bye

hi Gecamp,
thanx for your hint.
i have another question??!!
what is your idea about dynamicMeshDict for angular Oscillating displacement.
which method, solver and diffusivity should i use?!?

[desmoge]

Hi Pedram!
Well, I'm quite new regarding dynamic mesh movement. Here below you can find my setting which has worked so far but more runs need to go before I can develop a critical point of on it

dynamicFvMesh dynamicMotionSolverFvMesh;

motionSolverLibs ( "libfvMotionSolvers.so" );

solver displacementLaplacian;

diffusivity inverseDistance (solidGeometryName);


Now I've got a question for you, do you know how to run with OF the only mesh movement without solving the NS equations? I just need to check the motion quickly and I dont want to solve the whole flow fields.

[pedrampakzad2006]

Hi desmoge.
I have done the this and unfortunately in large amplitude it got an error!!!

And about your question...
You can solve your problem and after that, you can see the mesh changes in paraView.
In paraView you can set solid color and change surface to surface with edges.
Now you can run paraview and see the mesh motion.

[pedrampakzad2006]

Hi everyone. I want to analyze heat transfer of oscillating cylinder.
When I use inversedistance as diffusivity I didn't get a correct answer for nusselt number. It is same as the fixed cylinder.
What should I do?!?

[mr.sattari]

Originally Posted by desmoge

Hi Pedram!
Well, I'm quite new regarding dynamic mesh movement. Here below you can find my setting which has worked so far but more runs need to go before I can develop a critical point of on it

dynamicFvMesh dynamicMotionSolverFvMesh;

motionSolverLibs ( "libfvMotionSolvers.so" );

solver displacementLaplacian;

diffusivity inverseDistance (solidGeometryName);


Now I've got a question for you, do you know how to run with OF the only mesh movement without solving the NS equations? I just need to check the motion quickly and I dont want to solve the whole flow fields.

hi Gecamp
In order to only deform the mesh without doing any flow calculations the "moveMesh" utility can be used.