Definition of MRF Rotating Zone


#1

Hello everyone,

I am new to MRF simulations. I was wondering how to properly define (the dimensions) rotating zone during the mesh procedure? Let’s suppose I have a propeller and I want to simulate the flow field around it. Is the rotating zone defined as the disc (volume which will be intersected during the rotation) in which the propeller rotates? or it should be a little bit larger than this? if so, by how much.

I tried finding similar question on this forum but I was unable to do so. If there is a similar question in the forum, please tell me. Any help is appreciated. :slight_smile:

Regards
Abhishek VERMA


Community Digest September 2016
Cycloidal propeller
#2

Hello Abhishek,

Welcome! I tried to find the tutorial for this kind of problem but I cant quite find it, I know it is out there! Perhaps you would benefit by taking a look at my project and trying to apply some of the principles to yours? I always felt that examples help to learn significantly:

Rotating Zones

Let me know if it helps? (If it doesn’t, dont tell me! JK, let me know regardless!)

Good luck,

Oscar


#3

@oscarcorripio, thanks for providing that example. It’s a very good demonstration of how rotating zones should be set up.

Just to add here:

With the MRF approach, instead of “moving” the mesh which would create a high computational effort, we directly add the rotation of the air.

The MRF zone should be placed in the middle between the rotor and stator and it simply has to cover all the rotating parts - thus a close fit around the geometry is fine. It is recomended for it to be axial symmetric- for AMI it is a must, for MRF it is recommended


#4

And another good example you can have a look at is from the first session our drone workshop:

Step-by-Step Tutorial: Homework of Session 1 - Level 1


#5

Thanks @oscarcorripio and @AnnaFless for your reply. @AnnaFless is correct.

http://www.bcamath.org/documentos_public/archivos/publicaciones/OSCIC13_RAMEZANI.pdf.
http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.45.7691&rep=rep1&type=pdf

These papers says that the boundary of the MRF in an external flow field does not have much impact and therefore a close fit which is little bit larger than the geometry to guarantee that the interface is steady can properly define the zone.

Once again thank you very much guys for the help.