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-   -   MRF: how to validate of to know if things were set up correctly? (http://www.cfd-online.com/Forums/openfoam-verification-validation/99173-mrf-how-validate-know-if-things-were-set-up-correctly.html)

lovecraft22 March 27, 2012 15:25

MRF: how to validate of to know if things were set up correctly?
 
Hi all;
I'm simulating a spinning wheel with MRFSimpleFoam…
How would you check if my setup was correct?

epilson August 11, 2012 21:34

the easy way to validate is to find same study and after compare them...

this is the acadamic way to validate...

Aadhavan December 14, 2012 09:21

Hi Lovecraft22,
I am doing simulation of fan, I want to check case setup.
I want to conform my MRFZone file, I am bit confused.
the axis of rotation is (0 0 1),
origin (0 0 0 ) // how can we conform it?
omega 78.54 // is it should be - or +, for + setting I am not at all getting result.
for - RPM the result deviates 40%.

can you please suggest what should i do?

Thanks,
Aadhavan

lovecraft22 December 14, 2012 14:33

Hi Aadhavan;
I'm not sure I actually understood your question.

Btw, you need to specify:
1. your axis direction, for instance (0 0 1) if you want your axis direction to be aligned with the z-direction (meaning you body will rotate along this direction)
2. you axis origin, meaning the point your body will be rotating around, for instance (1 1 0), meaning that point will be located at those coordinates. Of course, if your axis direction is (0 0 1) then you can set whatever you want for the origin z coordinate as it will not matter.
3. omega, is the angular velocity at which your body rotates. It is chosen according the the right hand rule: point your thumb in the same direction as the axis and then your fingers will give you the positive direction for the velocity.

Hope this helps

Aadhavan December 17, 2012 05:46

Hi Lovecraft22,
Thanks for your reply, it seems that my settings are correct, but I dont know what factor is blocking the fan static pressure raise. I am getting only 40Pa static pressure raise but it should be 200Pa. I spend more than 2 months for this issue, still I am not able to figure out the problem.

Thanks,
Aadhavan

lovecraft22 December 17, 2012 15:11

It can be due to a large number of things, one could be the mesh on the fan (and on the surrounding region) for instance.

bioexplore January 2, 2013 23:44

Hi, lovecraft22, what is the dimension of omega? [rad/s] or [rpm]?

lovecraft22 January 3, 2013 03:55

Usually it should be rad/s otherwise you can change its units to be whatever you like.

maHein January 11, 2013 18:38

I use paraview to check if my MRF zone is set up properly. Just display the velocity vectors of the rotating walls. So you can check direction and magnitute of the rotational velocity easily.

bioexplore January 11, 2013 20:21

Quote:

Originally Posted by lovecraft22 (Post 399878)
Usually it should be rad/s otherwise you can change its units to be whatever you like.

Thanks lovecraft22, I have checked this in the development of U eqn in Rotating Frame, it showed that the omega's dimension should be rad/s.


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