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Old   September 10, 2021, 07:13
Default Rotating wheel
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costantino barro
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Hello I'm pretty new to this forum and also to Openfoam ambient. I'm having some doubts on my simulation maybe someone can give some advise.
I'm trying to replicate the case of a rotating wheel that I did on fluent.
My strategy was using the "rotatingWallVelocity" and apply a rotating speed to the surface of the wheel and solving the case with simpleFoam.
Despite obtaining some coherent results for the cd (meaning that I obtain the draft coefficient of a rotating wheel and not a stationary one), visual results in paraView do not agree with the previous conclusion.
As can be seen in the image I obtain a pressure field which is the one of a stationary wheel, because as far as I know a rotating wheel aligned with the flow should generate a Magnus effect (higher pressure on top and lower on bottom).
Also the streamlines doesn't seem to be affected that much by the rotation.



Here's the initial condition on velocity:


internalField uniform $flowVelocity;

boundaryField
{
//- Set patchGroups for constraint patches
#includeEtc "caseDicts/setConstraintTypes"

#include "include/fixedInlet"

outlet
{
type inletOutlet;
inletValue uniform (0 0 0);
value $internalField;
}

lowerWall
{
type fixedValue;
value $internalField;
}

lenticolare
{
type rotatingWallVelocity;
origin (0 0 0);
axis (0 1 0);
omega -38.32; // Rotational speed in radians/sec
}

#include "include/frontBackUpperPatches"
}
Attached Images
File Type: jpg pressure_field.jpg (21.7 KB, 29 views)
File Type: jpg streamlines_openFoam.jpg (90.9 KB, 32 views)
File Type: jpg streamline_fluent.jpg (78.6 KB, 29 views)
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Old   September 11, 2021, 06:55
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Hi,

Why don t use MRF ? As far as I understand your case MRF seems to be exactly what you need.
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Old   September 11, 2021, 07:28
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Yes, right now I'm trying to do it also with a MRF (as I did in fluent), which however seems to be quit complicated. The fact is that the full model is going to include also other parts which I think are going to interfere with the MRF volume and thus complicate even more the implementation of this system. So I was wondering what's is happening with the rotatingWallVelocity, and if it's correct to use it in this case
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Old   September 13, 2021, 09:04
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I was able to run a simulation with a MRF.
Results in paraview are still kinda strange so I was wondering if it's a problem deriving from the fact that paraView is not that good in showing results or if I'm setting the wrong boundary condition. The problem is that the flow outside and inside the MRF looks likes that are not connected. Anyway I'll post a few picture and the file of the boundary conditions
Attached Images
File Type: jpg streamline_insideMRF.jpg (33.0 KB, 23 views)
File Type: jpg streamline_MRF.jpg (39.1 KB, 24 views)
Attached Files
File Type: zip 0.zip (5.3 KB, 3 views)
File Type: zip system.zip (1.7 KB, 4 views)
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Old   September 13, 2021, 11:13
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Hi,

Could you share your constant directory too ?
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Old   September 14, 2021, 01:30
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First feedback,

You should add the AMI name interface in the file MRFProperties:
nonRotatingPatches (XXXX);

Do you mesh whith SnappyHexMesh ?
I think that you defined your AMI with the wall of your object. That could not work. You have to create a cylinder around your rotating object.

You should refer to the Propeller OpenFOAM tutorial to understand the preparation of AMI.
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Old   September 14, 2021, 07:09
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So in the nonRotatingPatches I should put the MRFstarorcyl, MFRrotorcyl, MRFstatorback, MRFrotorback ecc...?


I've used salome to build two separated mesh, one for the inside volume(the rotating one) and one for the external field (stationary) and then I created the AMI with the MRFstarorcyl, MFRrotorcyl, MRFstatorback, MRFrotorback ecc... surfaces
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File Type: zip constant(-polymesh).zip (1.8 KB, 4 views)
File Type: zip boundary.zip (967 Bytes, 3 views)
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Old   September 14, 2021, 12:04
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Ok but you have to use the function createPatch before starting your calculation.
Have a look at this video : https://www.youtube.com/watch?v=8JDK...annel=OlivierB

And all is in the propeller tutorial but the MRFproperties.

I will try to find 5min to check your files.
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