[CFD-Lover]

Hi,

I am working on developing an axisymmetric actuator disk code to study the flow over wind turbines. So far, I have come to a code where a volume source term was added to the momentum equation. The volume force varies in the radial direction and it is calculated such that a prescribedtotal thrust and torque is imposed on the fluid i.e. if you specify thrust and torque forces for any turbine, you can visualize the flow over it. I have verified the code for a specified thrust and torque and the results were in agreement with other CFD results. However, when I applied wedge boundary conditions on the same turbine i.e axisymmrtric, the velocity and pressure distributions were not in agreement with the 3d results. Is this the correct method or am I supposed to be specifying a 2D source term? I have verified results obtained using the wedge BC versus a full 3D simulation of an axisymmetric diffuser and as hoped, I got pretty decent agreement at a much lower computational cost. Attached is some results.


Axi results;


VAxi.png


3D results;

V3D.png

The code;
actuatorDiskSimpleFoam.zip

Thanks in advance for any suggestions.

[wyldckat]

Quick answer: I came looking into this post due to a PM you sent me. Took me quite a while to be able to look into this.

As far as I can figure out from your description, the problem is that you are not familiar with the "wedge" boundary: AFAIK, this is designed for when the flow goes parallel to the two wedge boundaries, it does not transfer fluid between the two boundaries.

What you are looking for is the "cyclic" boundary.

If you use the following command, you can find several tutorial cases that use the "wedge" boundary:

find $FOAM_TUTORIALS -name "*Dict" | xargs grep wedge

Similarly for cyclic boundaries:

find $FOAM_TUTORIALS -name "*Dict" | xargs grep cyclic

In the list given by last command, it's not very easy to see a tutorial case similar to yours, but I believe the tutorial "incompressible/SRFSimpleFoam/mixer" is similar to what you are looking for.

[CFD-Lover]

Dear Bruno,

Thank you very much for the reply. I have tried your suggestion by using Cyclic BCs. Surprisingly, both boundary conditions (either applying wedge or cyclic) led to the same results. I don't know what to do?

Regards,