CAE Simulation

Mesh Sensitivity Studies: Quantifying Simulation Integrity

In FEA and CFD, the mesh is the mathematical bridge between geometry and physics. A simulation result is only valid if it is "Mesh Independent"—meaning the results are a product of physics, not grid density. Edelweis performs Mesh Sensitivity Studies to eliminate discretization errors and ensure technical recommendations are built on stable foundations.

1. The Convergence Philosophy

The goal is to find the "Sweet Spot" where the mesh is fine enough for accurate gradients but coarse enough for efficiency. We track specific KPIs:

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KPI Selection: Tracking Maximum Von Mises Stress, Peak Displacement, Pressure Drop (ΔP), or Nusselt Number (Nu).
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Refinement Levels: Systematically generating Coarse (baseline), Medium (global densification), and Fine (gradient-focused) mesh levels.

2. Mesh Refinement Techniques

H-Refinement

Applying "Mesh Sinks" or Local Controls on critical fillets and contact interfaces where stress concentrations occur.

P-Refinement

Swapping from linear (1st-order) to parabolic (2nd-order) elements to represent curved geometry accurately.

Inflation Layers

CFD-specific prismatic layers at walls to resolve the Viscous Sub-layer and manage Y+ values.

3. Convergence Metrics & Reporting

Every Enterprise project includes a report proving the validity of simulation data:

Iteration	Element Count	Target KPI (Stress)	% Variance	Status
Mesh A (Coarse)	150,000	210 MPa	--	Baseline
Mesh B (Medium)	450,000	245 MPa	+16.6%	Unstable
Mesh C (Fine)	1,200,000	249 MPa	+1.6%	Converged
Mesh D (Ultra)	3,000,000	250 MPa	+0.4%	Diminishing Returns

4. Grid Convergence Index (GCI)

To meet aerospace and defense-grade standards, we calculate the GCI to estimate discretization error. This provides a "Confidence Interval" for the results (e.g., "Peak stress is 250 MPa ± 2%"), ensuring maximum reliability in high-stakes environments.

Technical Directives

Directive	Protocol
Singularity Check	If stress increases infinitely with refinement, it is flagged as a Singularity and resolved via FEA Methodology protocols.
Aspect Ratio Audit	We maintain element aspect ratios below 5:1 in critical zones to prevent numerical "stiffening."
Mass Balance Check	CFD studies must maintain a mass flow residual below 10⁻⁶ across all mesh levels.