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?

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

this is the acadamic way to validate...

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

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

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

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.

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

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

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.

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.

MRF-Stirrer Tank
 

Hi
I'm Simulating an agitating tank (Rushton Turbine Impeller). I create the geometry in Gambit and imported it in OpenFOam then I tried to run the Case and after a while I did it. But there is a big problem and it make me confused.
after running I check the velocity profile and I find out that the velocity is more higher than the real velocity. for example my omega is 100 and the radius of my impeller is 12 cm and the result of openFoam shows the velocity 22000 m/s !!!!!!!!!!
please help me.