COMSOL Multiphysics™

femmesh
FACE (EDGE NODES) FACE MID NODE
8,10,15,17 13
9,12,15,18 14
Hexahedral element (hex2):
23
14
15
16
9
24
25 27
26
17 20
18 21
19 22
10
11 13
12
The mid node number for each quadrilateral face of the hexahedral element can also
be seen in the following table.
FACE (EDGE NODES) FACE MID NODE
9,10,12,13 11
9,14,16,23 15
10,14,20,24 17
12,16,22,26 19
13,20,22,27 21
23,24,26,27 25
The mid node number for the hexahedral element is 18.
When importing meshes with reduced second order elements, also called
serendipity elements, the mid node of quadrilateral elements (or quadrilateral faces)
and the mid node of hexahedral elements must be added manually. The coordinates
for the mid node for a second order quadrilateral element (or quadrilateral face) is
calculated from the surrounding nodes according to
0.5*edgNodes-0.25*vertNodes, where edgNodes is the sum of the surrounding
(4) edge mid nodes and vertNodes is the sum of the surrounding (4) vertex nodes.
For a second order hexahedron, the coordinates of the mid node is calculated from
the surrounding nodes according to 0.25*edgNodes-0.25*vertNodes, where
edgNodes is the sum of the surrounding (12) edge mid nodes and vertNodes is the
sum of the surrounding (8) vertex nodes.
Degenerated elements (or collapsed elements), that is, elements where two or more
nodes refer to the same mesh point, are not allowed.
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