Boundary Layer Meshing

Boundary layer meshing is best accessed via the GUI.

To create a boundary layer:

  1. On the Command Panel, click on Mesh and then Boundary Layer.
  2. Click on the Create action button.
  3. Select System Assigned ID or manually enter an ID.
  4. On the Settings tab, enter the appropriate size for the first row in the boundary layer.
  5. Enter a value for the Growth Factor.
  6. Specify the Number of Layer.
  7. Optionally select Internal Continuity.

    Figure 1 - Settings Panel

    First row(a) -- the height of the first layer in the boundary layer

    Growth Factor(b/a) -- the factor by which each layer grows

    Number of Layers -- the number of layers that make up a boundary layer

    Internal Continuity  -- continuity flag for boundary layers.  If on, all intersections are a side type.

  8. On the Association tab, select Curve for 2D boundary layers or Surface for 3D boundary layers.

    For 2D boundary layers:

    1. In the Curve ID(s) field, enter the curve ID(s) where the boundary layer(s) begins.
    2. In the Surface ID field, enter the surface ID that contains the boundary layer(s).
    3. Click Add to add the curves to the boundary layer(s).
    4. Click Create to create the boundary layer(s).

    For 3D boundary layers:

    1. In the Surface ID(s) field, enter the surface ID(s) where the boundary layer(s) begins.
    2. In the Volume ID field, enter the volume ID that contains the boundary layer(s).
    3. Click Add to add the curves to the boundary layer(s).
    4. Click Create to create the boundary layer(s).

Figure 2 - Association Panel

For 2d boundary layers, a curve/surface pair is given to create a boundary layer starting from a curve and growing out on the given surface.

For 3d boundary layers, a surface/volume pair is given to create a boundary layer starting from a surface and growing out on the given volume.

Intersection Types

In some cases, the user may want to adjust the intersection types. This could be because the automatic intersection type is not desired, or because it is not workable due to ambiguity.

The four intersection types are:

These intersection types may be set on a vertex/surface basis and on a curve/volume basis.

Figure 3 - Intersections Type Panel

Current Limitations

Not all combinations of intersection types and topology are supported for 3d cases. An end, corner, or reversal may not span multiple curves in a single volume. A possible workaround is to composite the curves to make a single curve.

Not all meshing schemes may be used in combination with boundary layers. In cases where it is not supported, the boundary layer will be ignored in mesh generation.  It is supported with the following schemes:

Underlying Trelis Commands

Create Boundary_layer <id>

Delete Boundary_layer <id>

Modify Boundary_layer <id> add Curve <id_range> Surface <id>

Modify Boundary_layer <id> remove Curve <id_range> Surface <id>

Modify Boundary_layer <id> add Surface <id_range> Volume <id>

Modify Boundary_layer <id> remove Surface <id_range> Volume <id>

"*** Only three of the four parameters should be specified ***

"***           (Height, Growth, Layer, or Depth)           ***

Modify Boundary_layer <id> uniform Height <double> Growth <double> Layers <double> Depth <double>

Modify Boundary_layer <id> continuity {yes | no}

set boundary_layer intersection volume <id> curve <ids> type {end, side, corner, reversal, default}

set boundary_layer intersection surface <id> vertex <ids> type {end, side, corner, reversal, default}

Sample Journal Files

Example 1

reset

create surface rectangle  width 10 height 3

create surface circle radius 5 zplane

surf 2 move z -10

create volume loft surface 1 2  

delete surf 1 2

create boundary_layer 1

modify boundary_layer 1 uniform height 0.1 growth 1.2 layers 4

modify boundary_layer 1 add surface 4 volume 3 surface 5 volume 3 surface 6 volume 3 surface 7 volume 3

set boundary_layer intersection volume 3 curve 10 type side

set boundary_layer intersection volume 3 curve 12 type side

set boundary_layer intersection volume 3 curve 14 type side

set boundary_layer intersection volume 3 curve 16 type side

mesh vol 3

Example 2

reset

create surf rectangle wid 2

cylinder rad .1 z .1

cylinder rad .02 z .1

section volume 2 xplane reverse

section volume 3 xplane

volume 3 move x .5

create volume loft surface 12 8

unite volume 2 3 4

vol 2 copy

vol 5 scale .3 .3 1

vol 5 rotate -10 about z

vol 5 move x .55 y -.1

vol 2 5 move x -.25

imprint all

delete vol 2 5

surf all scheme trimesh

group 'profile' add curve 69 67 68 70 71 72 73 74

create boundary_layer 1

modify boundary_layer 1 uniform height 0.002 growth 1.2 layers 6

modify boundary_layer 1 add curve in group with name 'profile' surface 36

curve in group with name 'profile' size 0.02

surf 36 size .3

surface 36 sizing function linear neighbor 2

mesh surf 36