Wall Boundary Condition
The wall boundary condition would be applied to an external face or surface.
The flow velocity at the wall can be described by the following types:
- Moving Wall
- Used for surfaces in motion, where the tangential velocity component is specified.
- No-slip:
- Recommended for viscous flow and real-world surfaces where velocity is zero at the wall. This is set automatically with the Hex-dominant mesh.
- Rotating Wall
- Used to specify the rotation of a wall surface about an axis. The origin, axis of rotation, and angular velocity of the rotation must be specified. The latter could be specified as a constant, or as a time-dependent variable. This can also be inputted by uploading a CSV file.
- Slip
- This condition models a friction-less surface.
Additionally, to generate the boundary layer profile near wall regions, two approaches are available:
- Wall Function
- Full Resolution
Wall Function
Appropriate functions are used to model the velocity profile. Thus, the boundary layer profile is not completely calculated and a relatively coarse mesh can be used near wall regions.
Important Information
When using ‘Wall-function’, to achieve good accuracy, the y-plus for the first grid point must be in range
Full Resolution
In this case no functions are used and the profile is completely resolved. For this approach the mesh has to fulfill certain criterion and should be particularly of high resolution near wall regions.
Important Information
For 'Full Resolution' Y+ should be smaller than 1. This is highly recommended to capture the correct flow physics.