3 Reading and Manipulating Meshes

3.1 Mesh File Formats

The primary grid ingestion framework of the NeuralFlow solver is designed to interface seamlessly with industry-standard mesh generation software. Specifically, the system natively supports discretized spatial domains generated and exported from ANSYS Meshing or ANSYS Fluent (when operated in its dedicated meshing mode).

To ensure successful topological reconstruction and error-free ingestion within the GUIX-H environment, the imported grids must adhere to the following technical specifications:

• File Format and Extension: The computational mesh must conform strictly to the standardized ANSYS Fluent CFD grid format, typically designated by the .msh file extension.

• ASCII Encoding Requirement: In alignment with the solver’s predefined parsing constraints, the imported .msh file must be explicitly exported in ASCII text format. Binary-encoded mesh files are not supported in this release; attempting to load a binary grid will result in immediate file-reader failures or fatal parsing errors.

• Support for Saved CGNS Poly Grids: In addition to raw mesh files, the solver is fully capable of reading computational grids that have been previously parsed, validated, and saved as a polyhedral grid in the .cgns format. If a compatible .msh grid has been successfully ingested by the framework and subsequently written/saved as a CGNS poly grid, it can be reloaded directly into the workspace in future sessions, bypassing the raw mesh parsing stage.

• Supported Dimensionality and Topologies:

  • 2D Configurations: Full compatibility with 2D planar and 2D axisymmetric mesh layouts (with built-in support for coordinate translation to the radial axis of symmetry).

  • 3D Configurations: Robust support for standard 3D unstructured spatial topologies, including tetrahedral, hexahedral, pyramidal, prismatic (wedge) and polyhedral element configurations.

  CRITICAL WARNING: Topological Grid Constraints

  • No Cut-Cell Support: Cut-cell meshing techniques (such as Cartesian cut-cell grids) are currently not supported in this solver version.

  • Strict Face-Neighbor Connectivity: The numerical discretization schemes in NeuralFlow strictly require conformal cell-to-cell connectivity. Every interior face within the computational grid must be shared by exactly two adjacent cells, except domain boundary cells. Non-manifold face connections or arbitrary polygonal junctions will cause immediate solver initialization failures.

  • Prohibition of Hanging Nodes: Computational meshes containing hanging nodes (typically resulting from non-conformal local refinement, octree-based grid generation, or non-matching block interfaces) are strictly unsupported. Users must ensure that all grid interfaces are fully conformal and that no hanging nodes exist prior to exporting the .msh file.

3.2 Planar to Axisymmetric Conversion

For computational domains that exhibit rotational symmetry, the complex three-dimensional physical system can be reduced to a highly efficient two-dimensional formulation. This dimension reduction relies on the assumption that all flow-field and state-variable gradients in the azimuthal direction are negligible. Resolving these problems as axisymmetric domains significantly reduces the grid cell count, resulting in a drastically lower computational footprint and faster convergence while preserving exact physical fidelity.

To facilitate this modeling strategy, the GUIX-H framework incorporates a robust, bidirectional mesh conversion utility; from Planar-to-Axisymmetric and vice versa.

Coordinate Alignment Note: For all axisymmetric simulations, the numerical solver strictly defines the horizontal axis () as the radial axis of rotation. Users must ensure that their 2D mesh is correctly positioned relative to this datum. If the grid is offset, the translation tools within the Grid Toolbar should be utilized to align the geometry before executing the planar-to-axisymmetric conversion.

3.3 Checking Grid Metrics

This utility performs a rigorous diagnostic scan on the active computational mesh loaded into the solver, outputting a detailed topological and quality report directly to the Message View console. This enables immediate verification of the spatial dimensions, grid scale, and structural integrity of the domain prior to launching the simulation.

The printed diagnostic report catalogs the following specific grid parameters and metrics:

• Grid Dimension

• Grid Coordinate System

• Number of Nodes

• Number of Faces

• Number of Cells

• Volume

• Number of Cell Sections

• Number of Face Sections

• Number of Interface Sections

• Maximum Cell Volume

• Minimum Cell Volume

• Maximum Face Area

• Minimum Face Area

• Maximum Coordinate

• Minimum Coordinate

• Maximum Coordinate

• Minimum Coordinate

• Maximum Coordinate

• Minimum Coordinate

• Maximum Cell Aspect Ratio

• Maximum Cell Skewness

• Number of Skewed Cells

Following the presentation of these quantitative metrics, the diagnostic tool automatically runs a series of validation routines to identify potential geometric or topological flaws. If any severe mesh deformations, high-aspect-ratio anomalies, or cell quality warnings are triggered, a dedicated warning message is appended at the very end of the console printout to alert the user of potential numerical instability risks before solving begins.