🧮 y⁺ Calculator for CFD Grid Design

A lightweight and practical tool for CFD engineers to estimate near-wall grid spacing, skin friction coefficient, and boundary-layer parameters before mesh generation.
This repository provides both an executable tool and a technical LaTeX document explaining all the formulas and their references.

The package can be downloaded with following link, 👉 Download from Dropbox

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🚀 Features

• Executable Tool (Calculate_yPlus.exe)

  • Computes:
    • Reynolds number
    • Skin friction coefficient
    • Boundary layer thickness
    • First-layer grid spacing (ΔS)
    • Number of prism layers (N)
  • Supports cell-centered and vertex-centered solvers.
  • Reads and writes data via results.json for easy integration into GUI tools or automated workflows.
  • Designed for users of OpenFOAM, STAR-CCM+, Fluent, and other CFD solvers.

• Technical Documentation (CFD_yPlus_Documentation.pdf)

  • Written in LaTeX.
  • Explains all calculation formulas and their physical meaning.
  • Includes:
    • Skin friction coefficient correlations
      • Prandtl–Schlichting
      • ITTC-1957
      • Prandtl–Kármán
    • Boundary-layer thickness estimation (Schlichting, White)
    • First grid spacing for cell-centered vs node-based solvers
    • Prism layer count assuming a fixed stretching ratio (r > 1.0)

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📘 References

1. White, Frank M. Fluid Mechanics, 7th ed. McGraw-Hill, 2011.
2. Spurk, H. J. and Aksel, N. Fluid Mechanics. Springer Berlin Heidelberg, 2008.
3. Jin, S., Zha, R., Peng, H., Qiu, W., and McTaggart, K., 2024.
   Determination of Maneuvering Force Coefficients for a Destroyer Model with OpenFOAM.
   Journal of Ship Research, 68(02), pp.39–65.
4. Jin, S., Zha, R., Peng, H., Qiu, W., and Gospodnetic, S., 2020.
   2D CFD Studies on Effects of Leading-edge Propeller Manufacturing Defects on Cavitation Performance.
   SNAME Maritime Convention (p. D033S015R003).
5. Jin, S., Peng, H., and Qiu, W., 2024.
   Numerical Study on Effects of Leading-edge Manufacturing Defects on Cavitation Performance of a Full-scale Propeller.
   Physics of Fluids.

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🧰 Usage

📦 Download

The executable file (Calculate_yPlus.exe, 120 MB) is available here:

👉 Download from Dropbox