SimLab Volume Mesh Error (Overlap edges) - Conflict between MRF Fluid Interface and Boundary Layer G

Question

I am encountering an issue during volume mesh generation in Altair SimLab while working on a CFD model of a jet mill (including a high-speed rotating classifier wheel). I would like to seek your professional advice on the recommended workflow for this scenario.

[Model Setup]

* Topology: The model consists of two fluid bodies: Body 1 (Stationary domain) and Body 2 (Rotating MRF domain). An Imprint operation has been performed to ensure a conformal fluid-fluid interface.
* Surface Mesh: The surface mesh generates successfully. Mesh sizes: 3 mm global, 1 mm at the conformal interface, and 0.3 mm on the classifier blades.

[The Problem]When generating the Volume Mesh with Boundary Layers (BL) enabled, the mesher fails with the following error:Error:: Body 1 has overlap edges

Marc_21384 · Answer

Dear Gary,

Yes, the imprint didn't work. There are a couple ways of having a shared interface. The easiest is when creatin your surface mesh to enable the option "Create matching mesh". Please test it and let us know. Thank you!

Kind regards,

Marc

Chou · Answer

Dear Altair Support Team,

Thank you for the tutorial videos. I have followed the instructions to run further diagnostics on my mesh. Below are the results of my tests. Could you please advise if these indicate an issue with how my fluid interfaces are set up?

[Mesh Diagnostic Results]

* Free Edges Check: Using the 'Edges' tool, the system returned: "Element free edges not found."
* Individual Intersection Check: When selecting the two fluid bodies individually, it returned: "Element intersection not found." for both.
* Combined Intersection Check (Error): However, when I selected both fluid bodies together and ran the 'Intersection' check, the entire interface lit up in orange (as shown in the attached Image 2), indicating a massive mesh intersection and overlap between the two fluid domains.

[Additional Model Context]To clarify my setup:

* This is a CFD model of a Jet Mill.
* The entire model consists strictly of Fluid Domains; there are no solid bodies included.
* The red part shown in the images is an additional cylinder I specifically modeled to define the rotation of the internal Classifier Wheel (acting as the MRF rotating zone).
* The orange intersection errors occur exactly at the interface between this "red MRF cylinder" and the "Stationary Fluid Domain."

[My Questions]

Given that the individual meshes are fine but they intersect heavily when combined:

* Does this imply I missed a crucial step (such as Imprint) to properly define the shared fluid-fluid interface?
* Is this intersection issue the root cause of why I can successfully generate the Surface Mesh, but constantly fail to proceed to the Volume Mesh generation?
* I would greatly appreciate your recommended best practices for handling this specific MRF fluid interface setup in SimLab.

I have attached the screenshots of the intersection checks for your reference. Thank you very much for your continuous support!

Best regards,

Gary

Marc_21384 · Answer

Hello,

You can find videos on how to fix these problem in the learning center

https://learn.altair.com/pages/simlab-learning-center

Here are two that can specifically help you:

https://altair-2.wistia.com/medias/2g01s78quk

https://altair-2.wistia.com/medias/tzn79djdiq

https://altair-2.wistia.com/medias/2g01s78quk

Hope this helps!

Kind regards,

Marc