Introduction
The mesh divides the fluid domain into the cells on which the equations are solved.
Its geometry, connectivity, and resolution influence numerical stability and the flow features the calculation can represent.
Learning objective
Inspect the mesh report and distinguish mesh-quality checks from a mesh-refinement study.
Key idea
A mesh can pass its quality checks and still be too coarse to resolve the engineering quantities you need.
Understand the idea
Run the mesh-checking step specified in the starter and retain its complete output.
Review cell counts, boundary definitions, cell zones, and reported quality problems. Pay attention to issues such as non-orthogonality, skewness, and invalid cell volumes.
Inspect the mesh visually as well. Check the rotor region, narrow passages, near-wall cells, and transitions between fine and coarse regions.
Mesh quality and mesh sensitivity answer different questions:
- Mesh quality: Are the cells and their connections suitable for the numerical calculation?
- Mesh sensitivity: How much do the quantities of interest change when the mesh is refined?
A single successful mesh check cannot establish mesh independence.
Engineering example
Consider two meshes that both pass their quality checks.
One may contain relatively few cells near the blades, while the other resolves this region more closely. Their predicted pressure difference or torque may still differ.
That difference should be investigated through a controlled refinement study, with the other modelling choices held consistent.
Practical task
Save the mesh report and prepare screenshots of:
- The complete domain.
- The rotor region.
- A representative near-wall area.
- Any region associated with a reported warning.
Record which issues need attention before running the solver.
Checkpoint
Does “Mesh OK” prove that the final CFD result is accurate?
No. It indicates that the mesh passed the checks performed. Accuracy also depends on resolution, convergence, boundary conditions, physical modelling, and comparison with suitable evidence.
References
- The mesh-generation and checking instructions supplied with the starter.
- Examining Spatial Grid Convergence — NASA