https://cfmesh.com/tips-tricks-for-a-high-quality-meshing-process/

🧩 5 Tips and Tricks for a High-Quality Meshing Process

(Based on CF-MESH+ Blog Summary)

Preparing clean and well-defined geometry is essential for CF-MESH+ to generate high-quality meshes.
The following five tips help ensure smooth meshing and accurate CFD results.

🧠 Overview

Five key tips for high-quality meshing:

  1. Apply cell size smaller than half of the gap dimension.
  2. Modify geometry where the feature size tends to zero.
  3. Delete duplicate faces in the geometry.
  4. Remove unnecessary feature edges.
  5. Add feature edges where they are needed.

1️⃣ Apply Cell Size Smaller Than Half of the Gap Dimension

Purpose:
Ensure the surface mesh features are preserved when creating the volume mesh.

Key idea:
In narrow gaps (e.g., between shroud and blades in a compressor),
use cell size < ½ of the gap distance, ensuring at least two cell rows across the gap.

Otherwise:
Large cells may connect opposing surfaces, distorting flow regions and lowering simulation accuracy.

Illustrations:

  • Poor settings: surfaces merge, incorrect mesh features.
  • Proper settings: fine cells capture geometry separation accurately.

2️⃣ Modify the Geometry Where Feature Size Tends to Zero

Problem:
Sharp edges (e.g., airfoil trailing edges) create extremely small feature sizes.
No matter how fine the mesh is, cell distortion occurs if the feature tends to zero thickness.

Solution:

  • Round or blunt such edges to give them a finite feature size.
  • At these modified locations, make sure: $$ \text{cell size} < \frac{1}{2}(\text{upper surface distance} - \text{lower surface distance}) $$

Example:

  • Sharp trailing edge → distorted mesh.
  • Rounded/blunted edge → smooth, high-quality mesh.

Other case:
At small-angle junctions between surfaces:
add fillets or chamfers to help mesher handle transitions more efficiently.

3️⃣ Delete Duplicate Faces in the Geometry

Why important:

  • Duplicate faces confuse patch recognition.
  • They may generate unintended feature edges and create artificial constraints.
  • Multi-domain setups can fail or produce incorrect interface definitions.

Recommendation:

  • Clean the surface mesh from duplicates.
  • Afterwards: verify geometry continuity (avoid creating unwanted gaps).

✅ Clean geometry simplifies subset definitions and local refinements.

4️⃣ Remove Unnecessary Feature Edges

Issue:
Feature detection algorithms may mislabel smooth transitions as feature edges.
These redundant edges:

  • Add unnecessary meshing constraints,
  • May cause wrong patch detection, especially near intersections.

Action:
Inspect geometry visually and remove feature edges that don’t represent real physical boundaries.

Example:
On compressor blades, redundant edges should be deleted before meshing.

5️⃣ Add Feature Edges Where They Are Needed

Context:
The feature detection algorithm usually works well but isn’t perfect.
Missing edges may lead to loss of geometric detail (e.g., small corners or sharp changes).

Recommendation:

  • Perform a quick review of the surface mesh before meshing.
  • Add additional feature edges manually where geometric fidelity matters.

Effect of missing feature edges:
Geometry appears smoother than intended (e.g., wing tip losing edge definition).

🧩 Key Takeaways

Purpose Tip
Preserve small gaps Use smaller cell sizes (< half gap)
Handle sharp edges Round or blunt feature edges
Simplify patching Delete duplicate faces
Reduce overconstraints Remove unnecessary feature edges
Maintain geometry fidelity Add feature edges where missing

🛠 Tools and Versions

cfMesh (Open Source)

An open-source mesh generation library within OpenFOAM®.
Useful for automatic sizing, boundary layers, and polyhedral/tetrahedral meshing.
👉 More info

CF-MESH+ (Pro)

Enhanced commercial version — provides:

  • Improved boundary layer control,
  • Advanced mesh topology and quality management,
  • CAD import, multi-domain meshing, and
  • Built-in support and automation tools.
    💡 Free trial available

📜 References