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I am currently working on Conjugate Heat Transfer (CHT) simulations for a Triply Periodic Minimal Surface (TPMS) heat exchanger. While I've had great success with purely hydraulic (fluid-only) simulations, I am running into significant roadblocks when attempting to mesh both the solid and fluid domains simultaneously in Ansys Fluent.

What I've tried:

Simultaneous Meshing & Mesh Interfaces: My current method is to import and mesh both the solid and fluid domains together in Fluent Meshing, and then create a mesh interface in the solver to align them as best as possible.

The main issue is that this workflow severely restricts my boundary layers. If I attempt to generate more than 1 boundary layer, the volume mesh typically fails. This is not ideal for capturing the near-wall physics in these tight, complex lattice channels, which is likely hurting the accuracy of my results. When I was running single-domain hydraulic simulations, I had no limitations on boundary layer generation.

Questions:

Boolean/Subtract Workflows in Fluent: A national lab I collaborate with uses Star-CCM+, which allows them to import just one domain (e.g., the solid) and then generate the fluid domain via a Boolean subtract operation. Does Fluent Meshing have a similar Boolean, wrapping, or volume-extraction workflow that would make generating high-quality meshes on these TPMS structures easier?

Boundary Layer Generation: Has anyone found a reliable way to successfully grow multiple boundary layers on complex TPMS walls in a CHT setup without the volume mesh failing?

General TPMS Meshing Advice: Are there specific workflows (such as Watertight Geometry vs. Fault-Tolerant Meshing) or best practices for importing and meshing highly complex TPMS structures for multiphysics in Fluent? Any advice on a robust nTop-to-Fluent pipeline for CHT would be greatly appreciated. I've been following an nTop guide that uses fault-tolerant meshing workflow linked here: https://support.ntop.com/hc/en-us/articles/19341018332435-How-to-export-your-design-to-Ansys-Fluent.

Software Versions:

Ansys Fluent 2023 R2 

nTop 5.41.3