The domain comprises a 2D rectangular slab as shown below:

Case description


Several meshes are employed to highlight the sensitivity of the computed skin friction coefficient to the near wall \(y^+\) over the range \(0.05 < y^+ < 100\). All meshes are generated using blockMesh and employ the same number of cells whereby the first cell height is varied by changing the expansion ratio from the wall patch.


Mesh close-up

Boundary conditions

Common fields

Velocity: U

Patch Condition Value
Inlet fixedValue 69.4 m/s in x
Outlet zeroGradient  
Walls noSlip  

Pressure: p

Patch Condition Value
Inlet zeroGradient  
Outlet fixedValue 0 Pa (static)
Walls zeroGradient  

Turbulence viscosity: nut

Patch Condition Value
Inlet calculated  
Outlet calculated  
Walls nutUSpaldingWallFunction  

Turbulence fields

Inlet conditions are based on an inlet turbulence intensity of 0.0039%, and turbulence viscosity ratio of 0.009.

Turbulence kinetic energy: k

Patch Condition Value
Inlet fixedValue based on 0.039% intensity
Outlet zeroGradient  
Walls kqRWallFunction  

Turbulence specific dissipation rate: omega

Patch Condition Value
Inlet fixedValue based on nut/nu = 0.009
Outlet zeroGradient  
Walls omegaWallFunction  


The following figures show the predicted skin friction coefficient as a function of Reynolds number, compared against the experimental data from Weighardt [88]

Skin friction: low y-plus

Skin friction: high y-plus