Boundary layer 

Boundary layer mesh
These preferences control the boundary layer mesh properties.

• Stretching function: this variable set the stretching function which controls the height of each layer of boundary layer mesh. Options are the next ones, where 'h_i' is the height at level 'i' and 'r' is the grow factor:

·Function 1 (Geometric): This function is the geometric progression, and its expression is: h_i = h_0*(r^0+r^1+r^2+···+r^(i-1)
·Function 2 (Exponential): This function the exponential progression, and its expression is: h_i = exp(r*i + ln(h_0)).
·Function 3: This function is represented by: h_i = h_0 * (1 + i*(1+r*(1+r)*i))) . This function typically grows faster than the Geometric one.

• Grow Factor: This variable controls whether the stretching function grows slower (smaller values) or faster (bigger values). When Function 1 is used, grow factor must be greater than 1.0, and when Function 2 or 3 are used, grow factor must be a positive number.
• The red line below these options shows schematically the difference of height of the different layers of boundary layer mesh.
• Boundary layer mesh in separated Layer: if this preference is set, the mesh elements which own to a boundary layer mesh will own to separated layers. The name of these layers will be the same as the Layer name of the geometrical entity where elements are, but with the prefix 'BLM_'.