Mesh Quality#
After mesh generation, the Mesh Quality tab displays comprehensive quality metrics. Good mesh quality is essential for solver stability and accurate results.
Quality Metrics#
Skewness#
Measures how much a cell deviates from its ideal shape (e.g., a perfect hexahedron or tetrahedron).
Range |
Rating |
Impact |
|---|---|---|
0.0 – 0.25 |
Excellent |
Ideal for all solvers |
0.25 – 0.50 |
Good |
No issues expected |
0.50 – 0.85 |
Acceptable |
May slow convergence slightly |
0.85 – 1.0 |
Poor |
Can cause convergence failure |
Target
Maximum skewness should be below 0.85 throughout the mesh. Cartesian cells in the block AMR hierarchy have zero skewness by construction — poor skewness values only appear at cut-cells adjacent to geometry surfaces.
Non-Orthogonality#
The angle between the face normal vector and the vector connecting adjacent cell centers. Lower is better.
Range |
Rating |
Impact |
|---|---|---|
0° – 45° |
Excellent |
Fast convergence |
45° – 70° |
Good |
Standard for most solvers |
70° – 85° |
Acceptable |
May need non-orthogonal correctors |
> 85° |
Poor |
Solver instability likely |
Aspect Ratio#
The ratio of the longest cell dimension to the shortest.
Volume cells: Should be below 10 for the bulk mesh
Near-wall cut-cells: High aspect ratios are expected and acceptable in cells with aggressive near-wall AMR refinement — this is by design
Cell Volume#
All cells must have positive volume. Negative or zero-volume cells indicate a mesh error and must be resolved before simulation.
Quality Report#
The Mesh Quality tab shows:
Summary statistics — Total cell count, min/max/mean of each metric
Histograms — Distribution of cells across quality ranges for each metric
Threshold indicators — Visual markers showing what percentage of cells fall in each quality category
Interpreting Results#
Healthy Mesh#
95% of cells rated “Excellent” or “Good”
Maximum skewness < 0.85
Maximum non-orthogonality < 70°
No negative volumes
Marginal Mesh#
80–95% of cells rated “Excellent” or “Good”
A small number of poor-quality cells (< 1%)
May need non-orthogonal correctors enabled in solver settings
Poor Mesh#
Many cells with high skewness or non-orthogonality
Likely to cause solver divergence
Consider adjusting mesh settings and regenerating
Improving Mesh Quality#
If quality is not satisfactory:
Issue |
Solution |
|---|---|
High skewness near geometry |
Increase surface refinement AMR level |
High non-orthogonality at transitions |
Increase AMR levels for smoother size transitions between blocks |
Very small cut-cell volume fraction |
Geometry has tiny slivers — simplify or repair the surface |
Negative volumes |
Check geometry for self-intersections and repair |
Poor quality in narrow gaps |
Increase gap refinement AMR level or simplify geometry |
Quality vs. Cell Count Trade-off#
Higher quality generally requires more cells:
More AMR levels → Smoother transitions → Better quality
Smaller base cell size → More uniform sizing → Better quality
Higher surface refinement → Better cut-cell quality near geometry
Balance quality against your cell count budget and available compute credits.
Tip
The AI Assistant can interpret your quality report and suggest specific improvements. Ask: “How can I improve the mesh quality?”