Understanding and calculating Y+ (Y plus) is crucial for setting up accurate Computational Fluid Dynamics (CFD) simulations, especially when dealing with turbulence modeling and near-wall flow phenomena. Our online Y+ calculator helps engineers and students determine this dimensionless wall distance, ensuring optimal mesh resolution for your boundary layers.
Achieve reliable results by matching your mesh quality with your chosen turbulence model's wall treatment strategy for improved accuracy.
Formula:
The Y+ value is a dimensionless distance from the wall in turbulent boundary layers, defined as:
Y+ = (uτ · y) / ν
Where:
- uτ: Friction velocity, calculated as uτ = U · √(Cf / 2) (m/s)
- y: Distance from the wall (first cell height) (m)
- ν: Kinematic viscosity of the fluid (m²/s)
- U: Freestream velocity (m/s)
- Cf: Skin friction coefficient, estimated as Cf = 0.0592 · Rex-0.2 for turbulent flow over a flat plate (dimensionless)
- Rex: Reynolds number at distance x, calculated as Rex = (U · x) / ν (dimensionless)
- x: Characteristic length along the flow direction (e.g., distance from leading edge where Cf is evaluated) (m)