## Preprocessing

#### Cyclic symmetry generates problems with the meshing

• valeg
Subscriber

Hello to everyone! I'm trying to understand a problem that I have with the use of the cyclic symmetry. I modeled a very simple geometry and a applied the cyclic symmetry. I obtained also a good mesh using tetrahedrons method, but when I solve the model it gives me the following message: "An error occurred inside the solver module the mesh is corrupted. This could be due to the presence of a mesh connection or the objects in a body with cyclic". I really can't understand what is wrong. Can you please help me? The pictures of all the settings I put are attached. Thank you!

P.S. The model run if I just eliminate the symmetry and also works with the symmetry region. Only with the cyclic symmetry it gives this problem.

• peteroznewman
Subscriber

You should try to mesh this with a Method = Sweep.

• valeg
Subscriber

Thank you for the answer, but I already tried different type of mesh and the problem remains. Moreover, I can't obtain a good mesh with the Sweep method and the other ones as well, except for the tetrahedrons one.

• peteroznewman
Subscriber

Why do you need Cyclic Symmetry in the mesh? That is useful for CFD models. I don't see why you need it in a Structural model.

Don't you just have a pressure load on the inner face?  In that case, simple Symmetry is sufficient.

You will have faster solve times and better results if you use a hex mesh from a sweep method. Why can't you obtain a good mesh with sweep?

• valeg
Subscriber

With sweep method I have an error message from Ansys: "Mesher failed to mesh topological edges". Moreover I need cyclic symmetry in the model because I want to simulate in the end a quarter of a pipe subjected to an internal displacement or pressure. What do you mean for "simple symmetry"? In the symmetry module I have: Symmetry region, linear periodic and cyclic region. (I am new with Ansys software so every suggestions will be very appreciated!)

Thank you!

• peteroznewman
Subscriber

Use Symmetry region.  No need to use cyclic region. This discussion has a similar problem.

Open the geometry in SpaceClaim, go through the tools on the Repair tab. You should end up with a body with exactly 6 faces, 12 edges and 8 vertices. When you have that, you can get a clean Swept mesh.

• valeg
Subscriber

I did it. I have a geometry with exactly 6 faces, 12 edges and 8 vertices. The swept mesh works (in the previous model as well) without the cyclic symmetry. The symmetry region works, so it gives me a result, but it is not that I want. I guess that I can't model 1/4 of the pipe if I use the symmetry region, but I need 1/2, isn't it? Thank you for your time.

• peteroznewman
Subscriber

Did you look at the similar problem, that ended up only modeling a 30 degree slice of a pipe.

It is better to model 1/4 than 1/2 a pipe because the symmetry boundary conditions help to constrain the model.

• valeg
Subscriber

Thank you so much, I solved my doubts and the model works!