CFD Pre-Processing Tool · v2.0

y⁺ & Near-Wall
Mesh Calculator

Translate flow physics into precise near-wall mesh parameters — bridging theory and real-world meshing decisions.

ANSYS Fluent OpenFOAM STAR-CCM+ RANS / LES
Inputs
🌊 Flow Properties
e.g. 10–100 m/s for aerodynamics. High values (>100 m/s) may enter compressible regime.
Air at sea level ≈ 1.225 kg/m³ · Water ≈ 998 kg/m³
Air ≈ 1.8×10⁻⁵ Pa·s · Water ≈ 1.0×10⁻³ Pa·s
📐 Geometry
Chord / plate length for external flow.
🎯 Target y⁺
Preset: 1 → resolve viscous sublayer; 30–300 → wall functions
ℹ️ Engineering Assumptions
Assumptions Used in Calculations ▼
  • Turbulent, wall-bounded flow (correlations not valid for laminar regimes)
  • Smooth wall — no surface roughness effects
  • Zero pressure gradient (flat-plate / fully-developed approximation)
  • Incompressible flow: Mach number < 0.3 recommended
  • Empirical skin-friction correlations (Prandtl / Blasius)
  • Boundary layer estimated via Prandtl's 1/7-power law
  • Results are for preliminary estimation; final mesh should be validated via sensitivity study
Outputs
📊 Computed Mesh Parameters
🔬 Enter your flow parameters and click Calculate to see near-wall mesh recommendations.
Near-Wall Mesh Schematic
WALL SURFACE Δy₁ 1st cell height δ BL thickness FREE-STREAM FLOW → growth rate ~1.15–1.25
Applications
✈️
External Aerodynamics
Wings, fuselages, cars. Typically y⁺ ≈ 1 with k-ω SST for accurate drag/lift prediction.
🔩
Internal Pipe & Duct Flows
Hydraulic diameter governs Re. Wall functions (y⁺ 30–300) reduce mesh count significantly.
🌡️
Heat Transfer Simulations
Accurate y⁺ ≤ 5 required near heated walls to resolve thermal boundary layer gradients.
🔥
Combustion Chamber Walls
Extreme temperature gradients demand very fine near-wall resolution (y⁺ ≈ 1).
⚠️

Disclaimer: This calculator uses empirical correlations (Prandtl turbulent flat-plate, Blasius) for preliminary CFD mesh estimation and educational purposes. Results should be validated through mesh independence studies and comparison with published reference data. Assumptions include fully-turbulent, smooth-wall, incompressible flow with zero pressure gradient.