Improved roughness model for turbulent flow in 2D viscous‐inviscid panel methods

The present study presents a modified expression for the turbulent skin friction coefficient (Cf) in 2D viscous‐inviscid panel methods. The modified Cf expression includes surface roughness effects and is therefore believed to be an improvement to the modelling of leading edge roughness (LER) effect...

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Bibliographic Details
Published inWind energy (Chichester, England) Vol. 23; no. 3; pp. 608 - 616
Main Authors Olsen, Anders Smærup, Ramos‐García, Néstor, Bak, Christian
Format Journal Article
LanguageEnglish
Published Bognor Regis John Wiley & Sons, Inc 01.03.2020
Subjects
2D viscous‐inviscid panel method
Aerodynamics
Boundary layers
Closures
Coefficient of friction
Computational fluid dynamics
Computer simulation
Correlation analysis
Fluid flow
Friction
Kinetic energy
LE roughness
Mathematical models
Momentum
Parameters
Q3UIC
Reynolds number
Sand
Skin friction
soiled airfoil
Surface roughness
Surface roughness effects
Turbulent boundary layer
Turbulent flow
Two dimensional boundary layer
Two dimensional flow
Two dimensional models
Velocity distribution
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Summary:The present study presents a modified expression for the turbulent skin friction coefficient (Cf) in 2D viscous‐inviscid panel methods. The modified Cf expression includes surface roughness effects and is therefore believed to be an improvement to the modelling of leading edge roughness (LER) effects on airfoils. The basis for the study is the two‐equation viscous formulation used in 2D viscous‐inviscid panel methods, where the standard integral momentum and kinetic energy shape parameter equations are solved together with a number of turbulent closures. One of the closures relates the skin friction coefficient with the shape parameter and the momentum thickness Reynolds number. The relation is derived from Coles' law of the wake, which reasonably accurately describes any 2D turbulent boundary layer velocity profile. This is used to derive a new Cf‐expression with the Prandtl‐Schlichting sand grain roughness effect included, which is implemented in the Q3UIC code. Simulations on a NACA63‐418 profile with sand grain roughness on the forward part are compared with measurements and show an improved agreement with the measurements.
ISSN:1095-4244
1099-1824
DOI:10.1002/we.2445