Question about how to set up dynamic mesh for piston motion

[a1531318]

Hello, I am an undergraduate student, and I would like to ask for some advice.

My objective is to analyze fluid mixing inside a chamber caused by piston motion. Since piston motion requires the use of a dynamic mesh, I set up a dynamic mesh model and performed several simulations. However, the solution repeatedly fails to converge and eventually exceeds the critical limit.

For the mesh configuration, Body 1, which is the upper part of the chamber, was meshed using a tetrahedral mesh, while Body 2, which is connected to the lower chamber, was meshed using a sweep mesh.

When I ran the simulation with the dynamic mesh settings, I noticed that the mesh near the outer region could not deform or stretch as much as the mesh in the central region. As a result, the simulation loses convergence.

In this case, how should I approach the problem? I would appreciate any advice on which settings or mesh regions I should examine first.

I will attach some images, so please let me know if you need any additional information.

[Rob]

Have a look in Help, the incylinder (IC) tutorials/videos/content are what you're after. 

[a1531318]

Is there any way to fix the mesh tearing near the outer region even when using a UDF instead of ANSYS’s built-in in-cylinder function?

[a1531318]

Is there any way to fix the mesh tearing near the outer region even when using a UDF instead of ANSYS’s built-in in-cylinder function?

[Rob]

The built in functions are for the position, I was intending you look at the approach. Layering works well, and that should be sufficient for most piston systems. 

Note, if you're displaying mesh on a plane or iso-surface then you're not seeing a clean layer of cells, you're seeing the cut plane that may clip several.