Mesh Smoothing

  Centroid Area Pull

  Equipotential

  Laplacian

  Condition Number

  Mean Ratio

  Winslow

  Smoothing facet-based surfaces

After generating the mesh, it is sometimes necessary to modify that mesh, either by changing the positions of the nodes or by removing the mesh altogether. CUBIT contains a variety of mesh smoothing algorithms for this purpose. Node positions can also be fixed, either by specific node or by geometry entity, to restrict the application of smoothing to non-fixed nodes.

Mesh smoothing in CUBIT operates in a similar fashion to mesh generation, i.e. it is a two-step process whereby a smooth scheme is chosen and set, then a smooth command performs the actual smoothing. Like meshing algorithms, there is a variety of smoothing algorithms available, some of which apply to multiple geometry entity types and some which only apply to one specific type (these algorithms are described below.) To smooth the mesh on a geometry entity, the user must perform the following steps:

1. Set the smooth scheme for the object using the following command:

{Curve|Surface|Volume} <range> smooth scheme <scheme>

where <scheme> is any acceptable smooth scheme described in this section. Also set any scheme-specific information, using the smooth scheme setting commands described below.

2. Smooth the object, using the command:

Smooth {Curve|Surface|Volume|Hex|Tet} <range>

Groups of entities may be smoothed, by smoothing a group or a body.

If a Body is specified, the volumes in that Body are smoothed. If a Group is specified, only the volume meshes within these groups aresmoothed - no smoothing of the suface meshes is performed.

Typically, smoothing algorithms move nodes in order to improve the quality of the mesh on a given geometry entity. Smoothing is terminated either by satisfying a smoothing tolerance or by performing the maximum number of smoothing iterations. The smooth tolerance may be set by the user:

[Set] Smooth Tolerance <tol>

The value <tol> tells the smoother to stop when node movement is less than tol * the local minimum edge length. The default value for tol is 0.05. The maximum number of iterations may be set by the user: For volumes, the smooth tolerance and iterations may be set by the user but they are presently ignored by the smoothers:

Volume Smooth Tolerance <tol>

Volume Smooth Iterations <iters>

The default values are 0.05 for the tolerance and 18 * ( number of hexes / number of nodes )^(1/3)

Where used in the smooth schemes below, the Free keyword permits the nodes lying on the bounding entities to "float" along those entities; without this keyword, boundary nodes remain fixed.

Nodal positions may be fixed so that no smoothing scheme, either implicit or explicit, will move them, with the following command:

{Curve|Surface|Volume} <range> Node Position {Fixed|Free}

Node <range> Position {Fixed|Free}

The following command does not fix nodal positions, but does fix the connectivity of the mesh, preventing certain volume schemes from changing the bounding mesh:

{Curve|Surface|Volume} Mesh {Fixed|Free}

The specific smooth schemes available in CUBIT are now described in detail.