COMSOL Multiphysics™

elshape
Purpose
elshape
Define dependent variables and select shape functions.
Syntax
el.elem = 'elshape'
el.g{ig} = geomnum
el.tvars = 'on' | 'off'
el.geomdim{ig}{edim}.ind{eldomgrp} = domainlist
el.geomdim{ig}{edim}.shelem = meshcases | shapelist
meshcases.default = shapelist;
meshcases.case{elmcase} = shapelist;
meshcases.mind{elmcase} = caselist;
shapelist{eldomgrp}{3*ishape-2} = bmtypename
shapelist{eldomgrp}{3*ishape-1} = shapename
shapelist{eldomgrp}{3*ishape} = shapeparams
Description
The elshape element is responsible for allocating degrees of freedom and defining
dependent variables. For the syntax of the ind field, see elempty. The tvars field
turns the generation of time derivative variables on or off (default on).
The shelem field has a rather complicated syntax. If no alternate mesh cases are
defined, it is a cell array which for each domain group contains a cell array of triplets
bmtypename—shapename—shapeparams. The string bmtypename is a unique
identifier for a basic mesh element shape with certain additional properties, see the
table below.
TABLE 1-20: BASIC MESH ELEMENT TYPE IDENTIFIERS FOR ELEMENT TYPES GENERATED IN MESHES
NAME
DESCRIPTION
ls(0) 0D simplex (all elements are equivalent in 0D)
s(1)
ls(1)
s(2)
ls(2)
b(2)
lb(2)
s(3)
1D simplex, higher-order shape generated on boundaries in
2D and 3D
1D simplex, linear shape generated in 1D
2D simplex (triangle), higher-order shape generated on
boundaries in 3D and in a layer closest to boundaries in 2D
2D simplex (triangle), linear shape generated in the inner of
2D domains
2D brick (quadrilateral, quad), higher-order shape generated
on boundaries in 3D and in a layer closest to boundaries in
2D
2D brick (quadrilateral, quad), bilinear shape generated in the
inner of 2D domains
3D simplex (tetrahedron), higher-order shape generated in a
layer closest to boundary surfaces and free edges
106 | CHAPTER 1: COMMAND REFERENCE