MRF in CHT simulations

Project Support
1

Hi to all, is there any news regarding the chance to use MRF in CHT simulation? My target is to simulate a radial fan is sucking from the two planar face of the surrounding cylinder and blowing on the radial surface. Is the MRF approach the same of incompressible analysis ie the MRF volume is a a revolution volume intersecting the fluid volume where the fan blades are subtracted? in this case I think I had to ignore the interference warning message of fluid domain and rotating volume and both of them had to be the same material propriety assignment, right? many thanks Gp

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3

Hello,
do you have any news on this? I am stuck on this problem as well for a few days now.

4

I am trying to set up a MRF in a CHT sim, but if i assign the MRF a material, its just overlapping with the existing fluid region and does not interact with it in any way. Also then the fluid itself within the MRF gets “rotated” instead of the structure that should be “rotated”

5

Hi Tom,

The rotating zone is specified with a part that overlaps with the fluid volume. This part should not be assigned a material, and used only for the rotating zone advanced concept.

The effect of the rotating zone is to replace the effect of the rotation of the part with momentum on the fluid. Remember that this is a steady state simulation. If you want to see the walls to rotate, you will need a transient simulation and AMI rotating zone, but in my opinion this is not practical most of the times.

Please review the following pages for details:

6

Hi ggiraldof,
thanks for your reply! I tried not assigning a material to the MRF in my CHT simulation like i did in varoius incompressible simulations. Unfortunately, the simulation then fails because of not assigning a material to this zone.

7

Hi again,

Would you please send the URL to your project?

8

Hi, here is the link to a minimalistic example I set up a few days ago to study the problem:

Its goal is to simulate a spinning solid stirrer in a fluid, surrounded by a solid vessel and later introduce a heat source and study the heat transfer.

The simulation error because of MRF not beeing assigned a material you can see for example in CHT1, run 8. In the other CHTs and runs I tried various variations of the geometry, setup and mesh but nothing gave me the expected result, if any.

Thanks!

9

Hi, I think that you have a misconception on how to model the MRF zone.

You need to have one part to assign to the rotating region, in addition to the fluid volume. This part should intersect with all the parts you want to apply the rotating effect into.

For more illustration, please refer to the documentation as linked above.

10

Hi, i read the documentation concerning rotating zones prior to this project and successfully used several MRFs already in incompressible simulations.
The MRF in the example provided above (CHT1, run8) should be set up exactly like you described.

Is there a difference to modelling MRFs in incompressible simulations vs in CHT simulations?

Thanks