Radial Fan (MRF/RBM). Problem with Rigid Body Motion -RBM
 

Hello guys,
i simulate the fan behaviour of Moving Reference Frame MRF ("Frozen Rotor") and Rigid Body Motion RBM (Unsteady RANS).I have a problem with RBM.I got too much differential pressure.I thought the problem was with Geometry, but I made many changes to Geometry, but still nothing.
There Are Physics for 3 Regions-Housing/Inlet/Rotor.

Properties

Region Housing-Physics Values-Motion Specification --- //Stationary/ReferenceFrame for Rotation//

Region Inlet-Physics Values-Motion Specification ---- Stationary/ReferenceFrame for Rotation//

Region Rotor-Physics Values-Motion Specification ---//Rotation/LAbFrame for Rotation//

how i know the Region of Housing and of Inlet are Stationary and for that the Reference Frame must be Reference Frame for Rotation.
But if i change only in Housing Region the Reference Frame for Rotation to LabFrame for Rotation , i get a perfect solution. is it correct?
maybe you could help me ,i have a few days to find the reason .
Thank you

You should do both of the tutorials which cover MRF and RBM of a centrifugal fan. Everything is explained in detail...



My guess is that you mixed up reference frames which you used in MRF with an explicit motion specification that you have to use in RBM. RBM doesn't use different reference frames in rotating regions.

hi Chris13,
thank you for answering.
In region of rotating (RBM) i changed the <Motion> to <<rotating>>.IT is the same in tutorial and it is correct.But what about region of stationary? tutorial does not speak about .
Do i need to change by Stationary( Housing and Inlet) the <reference frame> to << Reference Fram to Rotating>> or just keep it to <<LAB refenence Frame>>,becouse i got a Discribtion List ,were was writtten that for Region Stationary (which is Housing and Inlet) Reference Frame must be changed to <<Reference frame for Rotation>>
When i simulate the Radial fan like in Tutotial ,i have no problem with solution.
but with this discription list from my Prof. ,i got counfused,becouse its not like in Tutorial.

Why would you specify anything other than Lab reference frame for the stationary region if it is supposed to stay stationary? And again, RBM does not use different frames of reference.



The tutorial doesn't speak about it because you never change it in the tutorial for the stationary region.


If your solution works, then why bothering with it? Just because you are not doing it as a recipe from your professor says? Sorry, I don't get it. Maybe the description is just about another case idk... Or - and that is just human - your professor made a mistake. Start thinking yourself instead of relying on descriptions. Sorry to be that honest.



Either way, what is the problem?

Thank you Chris for your advice. you're right!!!