Simulation run failed

Project Support
1

Hi Simscale,

I am trying to study the flow properties around a fin-bladed rotor. I have done all the setting and they all look good. But once I run the simulation, it failed after 3% of the simulation time.

Last time I ran the simulation on my first model of the fin-bladed rotor and it ran successfully. Hence, I am using the same setting for my current fin-bladed rotor model but this message is pop up in the Event log:

“The setup of sliding or periodic boundaries is invalid. If the mesh was uploaded, please make sure that the sliding/periodic boundaries are correctly defined. If the periodic boundary condition relies on a radial transformation, please consider using the complete geometry. If you are using a Hex-dominant mesher, try switching to the standard mesher instead. If none of the above is successful, please contact our support for assistance.”

What does it mean and how to fix it?

Here is the link of my project for your reference: SimScale

Thank you in advance for your help.

2

Hi Badrul,

I think the issue is related to the assignment of the symmetry plan and the wall of the flow volume intersecting the AMI region.

Can you please send me the project for which the setup has worked?

I tried a project with your geometry, where I set up a full-flow region and it was running fine.

Best regards
Sebastian

3

Thank you for the response. I really appreciate it.

I have to use the symmetry boundary region to save the computational cost since I am using the Standard Simscale account.

In fact, I used the same strategy for my previous project and it worked just fine. Is it because I am using different geometry for my current project?

Here is the link for my previous project: SimScale

Again thank you for your help.

4

Badrul,

To bounce off of Sebastian’s note, it is generally a best practice to work without a symmetry boundary with rotating zones as the transient behavior is often unsteady and asymmetrical in all axes (not just the axes normal to the axis of rotation as you are modeling). However, I understand making that assumption for the computational/time cost saving. As an aside, big props to you for setting up a set of successful transient simulations.

2 notes I wanted to add here:

  1. I would change the up the Wall Boundary Condition on the Fin Rotor faces to be of “Type = Rotating Wall.” This is automatic and redundant, but your no-slip wall is not the proper setup for rotating surfaces. Check out this link here for more information on the rotating wall boundary.

  2. While there are successful cases of using the Symmetry Boundary with the AMI rotating zone in contact with it, setups like these can be interpreted as invalid behind the scenes within the solver. A more appropriate boundary condition would be a Slip Wall Boundary Condition.
    The Slip Wall boundary acts similarly to the Symmetry boundary, in that it removes all normal components of the flow velocity and assumes only tangential velocities along the wall. If you visualize the flow domain was mirrored across that plane (as a symmetry boundary would model), then the normal component of velocity must be equal to zero across the plane as that would result in a discontinuity on that plane otherwise.

I hope this makes sense, but try progressing with the Wall Boundary set to Type=Slip on the face in contact with the AMI rotating zone. This should circumvent the error.

Cheers,
Omar