**bset

Description

This command creates a boundary set according to various input data. The syntax is the same as for the **nset command, except an ordered boundary is produced. A typical use is to generate first an nset using the **nset command, and then simple make a copy of it in the bset format using the *use_nset option. The command can also be used to find the outer boundary of an elset.

Syntax

The bset mesher takes the following command syntax:

**bset name \(~\,\) ... options

with the following options available:

*axes

switches the axes defining a cylindrical coordinate system when using the *plane selection. An example is *axes 1 3 2 where the cylinder is rotated about the \(2\) axis instead of the default \(3\)-rd axis.

*elset

elset1 … elsetN use only the nodes which are used by the given element sets. This can be used to make a “wrap” of separate elsets, or to easily limit the selection criterion.

*function

Create a bset using the nodes which satisfy the given function. Remember to include a semicolon at the end of the function definition.

*limit

Limit for nodes to qualify to be accepted by a function or plane function (default is 1.e-3).

*nodes

node1 … nodeN uses the given nodes to make up the set.

*plane

makes a boundary given a plane equation (4 real values). The 1st 3 values are the components of the plane normal, and the fourth is the intercept (or equiv. for cyl. coordinates).

*req_number

allows the user to set the number of nodes of the *use_nset option which must match the element faces in order to create the bsets. For example if the nset given includes just the edge nodes of an element around a corner, the “wrapping” face around the corner can be added.

*surface

Indicates that the set should be a bounding surface (outer) of the acceptable nodes (see also unshared_faces).

*type cartesian | cylindrical

set the type of coordinate system to be used with the *plane option.

*use_dimension

dim sets the dimension of bset to create. Normally the bset will be a faset for 3D meshes (the max space dimension found in the mesh), and will be a liset for 2D meshes.

*use_bset

bset-name use the nodes in the given bset to apply the criteria given. Several entries may be given.

*use_nset

nset-name make the nset named into a bset. Several entries may be given. This replaces the use of all nodes in the mesh to apply the selection criteria.

*start_near

It starts from the closest point to the specified vector (for 2D lisets).

*overwrite

Allows to overwrite the boundary set that has the same name.

*no_sort

disables the ordering of 2D boundary sets (liset).

Example

To create the outer “wrapping” surface (unshared) for the element set PIPE2:

**bset wrap1
 *surface
 *elset PIPE2

Making an outer face at a radius of 20.

**bset face_r=20
 *limit 1.e-3
 *type cylindrical
 *plane 1. 0. 0. 20.

More examples are given for the *nset in nset.