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-   -   Single Rotating Frame with MRFSimpleFoam (http://www.cfd-online.com/Forums/openfoam-solving/58867-single-rotating-frame-mrfsimplefoam.html)

david May 16, 2008 11:08

Hi everybody! I'm trying to
 
Hi everybody!

I'm trying to simulate a modified version of the mixerVessel2D case with MRFSimpleFoam. The stator should rotate with the same angular velocity as the rotor. For this reason I assigned all the cells to the cellZone rotor by modifying blockMeshDict.m4. I also modified constant/MRFZones so that the patch stator is rotating too.

Unfortunately I'm getting pretty high velocities and I don't know why.

http://www.cfd-online.com/OpenFOAM_D...ges/1/7703.jpg

Here are the modified files:

http://www.cfd-online.com/OpenFOAM_D...hment_icon.gif blockMeshDict.m4
http://www.cfd-online.com/OpenFOAM_D...hment_icon.gif MRFZones

Is it possible at all to simulate a Single Rotating Frame with MRFSimpleFoam or did I make a mistake? Any help would be really appreciated.

Regards
David

david May 19, 2008 05:51

I forgot to say that I'm using
 
I forgot to say that I'm using a value of 314.157 for omega. The highest velocity should be around 31.5 m/s and not 60 m/s. Any ideas?

Thanks
David

david May 19, 2008 09:34

Ok, sorry guys. I found the pr
 
Ok, sorry guys. I found the problem. It was my mistake ;-)

dmoroian May 19, 2008 10:06

Hi David, I just tried a simi
 
Hi David,
I just tried a similar case with yours and it works (omega =104.72 rad/s; radius = 0.514 m -> v = 53 m/s):
http://www.cfd-online.com/OpenFOAM_D...ges/1/7725.jpg

Dragos

david May 20, 2008 08:21

Hi Dragos Thank you very mu
 
Hi Dragos

Thank you very much for helping me. Unfortunately I can't understand why it worked with your case while it didn't work with my case??

My problem was that I didn't set up the case correctly. I found two different solutions for my problem:

Solution 1:
- Assign all the cells to cellZone rotor in blockMeshDict.m4
- Move the faces from patch stator to patch rotor and delete patch stator in blockMeshDict.m4

Solution 2:
- Assign the rest of the cells to cellZone stator.
- Modify makeMesh and the dict-files so that all the operations are made for rotor & stator.
- Change MRFZones in the following way:

2
(
rotor
{
patches (rotor);
origin origin [0 1 0 0 0 0 0] (0 0 0);
axis axis [0 0 0 0 0 0 0] (0 0 1);
omega omega [0 0 -1 0 0 0 0] 314.159;
}

stator
{
patches (stator);
origin origin [0 1 0 0 0 0 0] (0 0 0);
axis axis [0 0 0 0 0 0 0] (0 0 1);
omega omega [0 0 -1 0 0 0 0] 314.159;
}
)

Regards
David

david May 20, 2008 09:58

Solution 1b: - Assign all the
 
Solution 1b:
- Assign all the cells to cellZone rotor in blockMeshDict.m4
- Change MRFZones in the following way:

1
(
rotor
{
patches (rotor stator);
origin origin [0 1 0 0 0 0 0] (0 0 0);
axis axis [0 0 0 0 0 0 0] (0 0 1);
omega omega [0 0 -1 0 0 0 0] 314.159;
}
)

dmoroian May 20, 2008 10:04

Hello David, From what I unde
 
Hello David,
From what I understand, you want to rotate everything, so you should assign all the cells to the rotor.
Basically, you are after a rotating rigid body solution.

Dragos

david May 22, 2008 04:25

Hi Dragos That is exactly w
 
Hi Dragos

That is exactly what I wanted to do. My intention was to play with a simple case to understand it. Now I'm trying to simulate a pump impeller.

Regards
David


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