Open this dialog via the green Parameters button on the BL parameters subpanel when you select Smooth BL from the toggle in the bottom-left corner of the panel.  

The Minimum (Tetrahedral-Core/Boundary Layer) thickness ratio value is the minimum ratio between the thickness of the tetrahedral core and the boundary layer. This value must be more than zero, but decimal values are accepted. The higher this value, the more the boundary layer elements will be compressed to keep the core open.

The Bound Layer thickness at corners adjusts the total thickness of boundary layers in corners to avoid elements getting distorted or interfering with other boundary layer elements because of the default hyperbolic growth of the boundary layer. The smaller this value is, the smaller the thickness of the boundary layer at corners will be relative to the nominal total boundary layer thickness. The image below shows the effects on the same model using values of 1 and 5.

 

 

See Also:

CFD Tetramesh Panel